Alleged racist tweet directed at Muamba

South Wales Police on Sunday arrested a man over "racially offensive" tweets he allegedly wrote about Bolton midfielder Fabrice Muamba, who is fighting for his life after suffering a cardiac arrest on the field.

"South Wales Police have arrested a 21 year old male from the Ponty Pridd area in connection with racially offensive comments made on the social media site Twitter," the police force said in a statement.

Authorities have not revealed the man's name nor have they published the tweets that lead to his arrest. The suspect is in custody at Swansea Central Police station.

Sky News reported that the comments appeared on the Twitter account @liamstacey9, which has since been disabled.

Muamba stopped breathing after collapsing on the field late in the first half of Bolton's televised FA Cup quarterfinal clash with Tottenham Hotspur at White Hart Lane on Saturday.

The 23-year-old African player received life-saving treatment from on-site medical staff amid shock in the stadium, with several players visibly overwhelmed by his sudden collapse.

He is currently in the intensive care unit of the London Chest Hospital's world-class heart attack center. Bolton manager Owen Coyle earlier described the coming day as "absolutely crucial" in Muamba's bid to stay alive.

Coyle urged fans to keep Muamba in their prayers, saying, "We've obviously been inundated with people wishing him well. And we hope that if everybody can pray strongly that Fabrice is able to recover."

Muamba came to the UK with his family in 1999, fleeing the guerilla war in Zaire, now the Democratic Republic of Congo.