A joint statement was issued by the London Chest Hospital and Bolton football club amid reports Muamba has been talking from his hospital bed. The statement read: "Fabrice Muamba remains in intensive care at the London Chest Hospital. He is continuing to show signs of improvement this evening.
"He is now able to breathe independently without the aid of a ventilator. He has also been able to recognise family members and respond to questions appropriately.
"These are all positive signs of progress. However, the medical staff in intensive care will continue to monitor and treat him.
"His family and club would like to thank the media for continuing to respect their privacy at this time."
Muamba's friend, Curtis Codrington, said the family had told him the player was speaking "minimal words in English and French.
Earlier the hospital confirmed that Muamba's heart was now beating without the help of medication and that he was also moving his arms and legs.
The statement added: "However, his long-term prognosis will remain unclear for some time."
The encouraging news came after Bolton's captain Kevin Davies said his players have had "sleepless nights" over their team-mate's collapse on the pitch at Tottenham.
Davies told Sky Sports News players were "holding out and hoping he can pull through".
He said: "It's been sleepless nights, with what we saw in the pitch.
"You're half expecting the phone to ring with what we saw."
Describing the moments after Muamba collapsed, he said: "We all knew there was something seriously wrong.
"He's one of your colleagues, one of your friends, a father, a son - you just feel powerless to do anything about it."
Bolton Wanderers manager Owen Coyle later spoke of Muamba's "brave fight".
He told reporters the family had been "inundated" with messages of support for Muamba, whose heart stopped for two hours after he fell to the ground at White Hart Lane in front of millions of television viewers watching the quarter-final clash.
Paramedics made continued efforts to resuscitate him but were unable to start his heart beating by itself again until he reached hospital at 8pm.
Relatives, including Muamba's brother and fiancee, and fellow footballers such as Spurs striker Jermain Defoe and Arsenal defender Johan Djourou have been among his visitors there.
Muamba's fiancee, who goes by the name Shauna Muamba on Twitter and is mother to their son Joshua, wrote on the social networking site: "God is in control. Please keep @fmuamba in ur prayers xx"
She later added: "Please keep praying for @fmuamba its really helping I can feel it xx".
Another post said: "For all your messages of love thank u so much. Where there is life there is hope xx"
After visiting Muamba in hospital on Monday, Coyle said: "The message is the good will, the prayers from everybody, they are so thankful and they want to put that on record - to say 'keep up the prayers, thanks for all the support'.
"They have been inundated as we all have, both in the football community globally and family and friends.
"People are taking a genuine interest and a real concern with how Fabrice is doing."
Meanwhile, Wanderers have postponed their Premier League tie against Aston Villa, which was due to take place on Tuesday evening, and a reserve fixture against West Bromwich Albion, which was supposed to happen on Wednesday.
A joint statement by the London Chest Hospital and Bolton said he continued "to show signs of improvement".
It added his condition was no longer critical but remained serious.
The former England Under-21 player has been at the hospital's heart attack centre after suffering the cardiac arrest during Saturday's FA Cup quarter-final at White Hart Lane.
His fiancee, Shauna Magunda, the mother of his son Joshua, posted on Twitter on Monday evening: "All your prayers are working people thank you so so much. Every prayer makes him stronger."
A family friend, Curtis Codrington, also tweeted that he had visited Muamba in hospital on Monday night. He said the player was as "strong as an ox".
"He said my name words can't describe what I just saw," he added. "To see his wife, to be by his side was great."
"The support we had from Tottenham and our own fans was fantastic - the staff, the fans, the players and the officials at the game - it was unbelievable."
Manager Owen Coyle said: "Everybody is praying for Fabrice, which is very important and that has been a real source of strength to the family."
Meanwhile, Bolton captain Kevin Davies said that suggestions about the club withdrawing from the FA Cup because players were too upset to return to White Hart Lane were "irrelevant" as everybody was focused on Muamba's health.
Blackburn Rovers manager Steve Kean also said the club would "do whatever we have to do", and would be happy for Saturday's scheduled Premier League match against Bolton to be called off.
Muamba was born in Zaire, now Democratic Republic of Congo, and moved to England aged 11 as a refugee.
DR Congo FA president Omari Selemani said the midfielder had the support of "65 million" Congolese.
"On the behalf of the Congolese FA, all the Congolese people and myself included, we express our sympathy to Fabrice Muamba."
In the past the player has rejected attempts by the Congolese FA to call him up, choosing instead to play for England at youth level.
The score was 1-1 when the quarter-final was abandoned after 41 minutes.
It took medical staff two hours to get Muamba breathing again, and they gave him mouth-to-mouth resuscitation as well as trying to revive him with a defibrillator.
Both sets of supporters chanted Muamba's name as he was taken off the pitch on a stretcher.
Spurs manager Harry Redknapp said at the time: "All we are thinking about now is Fabrice and his family."
Referee Howard Webb called the visibly-shaken players off the field after consulting with Coyle and Redknapp and the game was abandoned.
Read more on this story:
:: Man Admits Making Racist Muamba Tweets
:: Profile: Muamba's Battle To Get To The Top
:: 'Shocked' Spurs Players Demand Heart Checks
For all your messages of love thank u so much. Where there is life there is hope xx
"These are all positive signs of progress. However, the medical staff in intensive care will continue to monitor and treat him.
"His family and club would like to thank the media for continuing to respect their privacy at this time."
Muamba's friend, Curtis Codrington, said the family had told him the player was speaking "minimal words in English and French.
Earlier the hospital confirmed that Muamba's heart was now beating without the help of medication and that he was also moving his arms and legs.
The statement added: "However, his long-term prognosis will remain unclear for some time."
The encouraging news came after Bolton's captain Kevin Davies said his players have had "sleepless nights" over their team-mate's collapse on the pitch at Tottenham.
resuscitation expert: everyone should learn first aid
He said: "It's been sleepless nights, with what we saw in the pitch.
"You're half expecting the phone to ring with what we saw."
Describing the moments after Muamba collapsed, he said: "We all knew there was something seriously wrong.
"He's one of your colleagues, one of your friends, a father, a son - you just feel powerless to do anything about it."
Bolton Wanderers manager Owen Coyle later spoke of Muamba's "brave fight".
He told reporters the family had been "inundated" with messages of support for Muamba, whose heart stopped for two hours after he fell to the ground at White Hart Lane in front of millions of television viewers watching the quarter-final clash.
Muamba Off Ventilator
Relatives, including Muamba's brother and fiancee, and fellow footballers such as Spurs striker Jermain Defoe and Arsenal defender Johan Djourou have been among his visitors there.
Muamba's fiancee, who goes by the name Shauna Muamba on Twitter and is mother to their son Joshua, wrote on the social networking site: "God is in control. Please keep @fmuamba in ur prayers xx"
She later added: "Please keep praying for @fmuamba its really helping I can feel it xx".
Another post said: "For all your messages of love thank u so much. Where there is life there is hope xx"
After visiting Muamba in hospital on Monday, Coyle said: "The message is the good will, the prayers from everybody, they are so thankful and they want to put that on record - to say 'keep up the prayers, thanks for all the support'.
"They have been inundated as we all have, both in the football community globally and family and friends.
"People are taking a genuine interest and a real concern with how Fabrice is doing."
Meanwhile, Wanderers have postponed their Premier League tie against Aston Villa, which was due to take place on Tuesday evening, and a reserve fixture against West Bromwich Albion, which was supposed to happen on Wednesday.
Fabrice Muamba "has been able to recognise family members and respond to questions appropriately", his club Bolton and hospital have jointly said.
The 23-year-old can "breathe independently" without a ventilator but remains in intensive care after a cardiac arrest on Saturday. A joint statement by the London Chest Hospital and Bolton said he continued "to show signs of improvement".
It added his condition was no longer critical but remained serious.
Use accessible player and disable flyout menus 
An earlier statement had said "he is also moving his arms and legs" but "his long-term prognosis will remain unclear for some time". James Pearce reports from the London Chest Hospital about Fabrice Muamba's condition
The former England Under-21 player has been at the hospital's heart attack centre after suffering the cardiac arrest during Saturday's FA Cup quarter-final at White Hart Lane.
His fiancee, Shauna Magunda, the mother of his son Joshua, posted on Twitter on Monday evening: "All your prayers are working people thank you so so much. Every prayer makes him stronger."
A family friend, Curtis Codrington, also tweeted that he had visited Muamba in hospital on Monday night. He said the player was as "strong as an ox".
"He said my name words can't describe what I just saw," he added. "To see his wife, to be by his side was great."
Fabrice Muamba factfile
- Born on 6 April 1988 in Kinshasa, Democratic Republic of Congo
- Progressed through Arsenal's youth academy, representing England at every level from Under-16 to Uunder-21
- Joined Birmingham City in 2007, having been there on loan previously, then moved to Bolton Wanderers the following year
- Appeared at the 2011 European Under-21 Championship in Denmark for England Under-21s, for whom he made 33 appearances
Club chairman Phil Gartside and manager Owen Coyle visited the player on Monday morning.
In a statement placed on the club website, Gartside said: "The staff at the London Chest Hospital have been nothing short of exceptional and I would like to thank them all at this ongoing critical time. "The support we had from Tottenham and our own fans was fantastic - the staff, the fans, the players and the officials at the game - it was unbelievable."
Manager Owen Coyle said: "Everybody is praying for Fabrice, which is very important and that has been a real source of strength to the family."
Meanwhile, Bolton captain Kevin Davies said that suggestions about the club withdrawing from the FA Cup because players were too upset to return to White Hart Lane were "irrelevant" as everybody was focused on Muamba's health.
Use accessible player and disable flyout menus 
Bolton's next Premier League game at Aston Villa on Tuesday has been postponed. Bolton captain Kevin Davies says talks about the club withdrawing from the FA Cup are irrelevant
Blackburn Rovers manager Steve Kean also said the club would "do whatever we have to do", and would be happy for Saturday's scheduled Premier League match against Bolton to be called off.
Muamba was born in Zaire, now Democratic Republic of Congo, and moved to England aged 11 as a refugee.
DR Congo FA president Omari Selemani said the midfielder had the support of "65 million" Congolese.
"On the behalf of the Congolese FA, all the Congolese people and myself included, we express our sympathy to Fabrice Muamba."
In the past the player has rejected attempts by the Congolese FA to call him up, choosing instead to play for England at youth level.
Use accessible player and disable flyout menus 
Medics spent six minutes trying to resuscitate Muamba on the pitch after he fell to the ground with no other players around him. Steve Kean said he would be happy to reschedule Blackburn's match against Bolton
The score was 1-1 when the quarter-final was abandoned after 41 minutes.
It took medical staff two hours to get Muamba breathing again, and they gave him mouth-to-mouth resuscitation as well as trying to revive him with a defibrillator.
Both sets of supporters chanted Muamba's name as he was taken off the pitch on a stretcher.
Spurs manager Harry Redknapp said at the time: "All we are thinking about now is Fabrice and his family."
Referee Howard Webb called the visibly-shaken players off the field after consulting with Coyle and Redknapp and the game was abandoned.
Read more on this story:
:: Man Admits Making Racist Muamba Tweets
:: Profile: Muamba's Battle To Get To The Top
:: 'Shocked' Spurs Players Demand Heart Checks