Luis Suarez "must face a severe sanction" if he is found to have bitten an Italian player during a World Cup match, a senior Fifa official has told Sky News.
Speaking on condition of anonymity, a senior official from international football's governing body said the Liverpool star "must face a severe sanction. If we allow this where will it stop?"
Fifa has opened disciplinary proceedings against Luis Suarez after he was accused of biting Italy defender Giorgio Chiellini.
The striker and the Uruguayan FA have until 9pm UK time to "provide their position and any documentary evidence they deem relevant".
Uruguay trained in Natal on Wednesday morning, but Suarez and his teammates who played against Italy were given a day off to rest.
Suarez has already commented on the incident, declaring: "These things happen on the pitch."
The Uruguay striker has previous after biting Chelsea's Branislav Ivanovic
The striker clashed with Chiellini in the 79th minute of his country's Group D match, a game they won 1-0 to advance to the last 16.
Television replays show Suarez moving his head towards Chiellini and apparently sinking his teeth into his shoulder, with Chiellini responding by swinging his arm.
Defending the alleged attack, Suarez said: "We were both just inside the area, he struck me in the chest with his shoulder and he hit me in the eye as well.
"These are things that happen on the pitch and you shouldn't attach so much importance to them.
"I'm very happy to have qualified. We are taking each game as it comes, we know that we're in a difficult situation, we're at our limits now."
Speaking to Rai TV after the game, Chiellini said: "It was ridiculous not to send Suarez off.
Suarez was sent off for a notorious handball in South Africa in 2010
"It is clear, clear-cut and then there was the obvious dive afterwards because he knew very well that he did something that he shouldn't have done."
Article 77 of Fifa's disciplinary code allows it to hit players with retrospective bans of up to two years if it decides there is a case to answer.
Daily Mirror football writer Darren Lewis told Sky News' Sunrise programme he believes Suarez faces a lengthy international ban, but is likely to escape punishment that would prevent him from playing for Liverpool.
Both Adidas and betting firm 888poker - two of Suarez's key sponsors - have announced they are reviewing their relationship with the player following the alleged bite.
Suarez served a 10-match ban last year for biting Chelsea defender Branislav Ivanovic.
Before his move to Liverpool in 2011, Suarez was suspended for seven matches by the Netherlands football federation after biting PSV Eindhoven's Otman Bakkal when he played for Ajax.
He also received a eight-match ban in 2011 after the Football Association found he had racially abused Patrice Evra seven times during a game against Manchester United. He has never apologised to Evra.
Professor Cary Cooper from Lancaster University told Sky News that if the forward is found guilty in this latest incident, he should get professional help.
He said: "For anyone in a job who's behaved in an anti-social way, they should be helped - you go to a clinical psychologist, a counselling psychologist and they would try to unwrap why you do that, and then channel that in a more positive way."
He said any ban should also include an order or encouragement for Suarez to get help for his behaviour.