Mike Tyson's opponent Julius Francis could face bankruptcy if the American is not allowed into the UK by immigration officers.

Francis' promoter, Frank Maloney, told BBC News Online the south London fighter had spent £70,000 on a training camp and other expenses, fully expecting to receive a £350,000 purse at the end of the month.

Tyson and his American entourage have confirmed they will definitely arrive in London on Sunday, despite warnings from the government that the former world heavyweight champion may be barred from entry because of his criminal convictions.

Fight promoter Frank Warren says he stands to lose £600,000 of his own money if Tyson is not allowed into Britain.

And Maloney admitted his man could face bankruptcy proceedings, saying: "He has been promised a £350,000 purse but by the end of the training camp he will have spent £70,000 of that."

Maloney, who also promotes world heavyweight champion Lennox Lewis, admitted the row was "seriously unsettling" Francis.

But he said: "We are trying to keep it away from him. We've told him it's a little problem which will be resolved.

"He has access to newspapers and the radio but it is monitored," said Maloney.

The scene is set for a showdown at Heathrow airport between Tyson and immigration officers.

Warren has accused some Labour MPs of playing politics with the boxer.

"The problem we have got now is that some poor guy has got to make a decision with all this pressure," Warren said.

"At one stage the Prime Minister was saying he shouldn't be let in, so the Prime Minister is saying don't you make that decision.

"I got a letter on Wednesday from (the Prime Minister's press secretary) Alastair Campbell.

"He sent me a letter saying I was wrong on TV to say that this Government was wrong to interfere.

"He said he didn't say Mike Tyson had little chance of coming to Britain, he said it was a matter for the immigration department."

A spokesman for Warren's Sports Network firm, John Finch, told BBC News Online it was too late to change the venue to another country.

But he pointed out the Tyson fight was only an "undercard" fight - the main attraction is Joe Calzaghe's title defence against David Starie - and if it fell through they might have to refund some tickets and change to a smaller venue.

He accused the press of whipping up the controversy and added: "Loads of people have been let into this country, having served time. Just look at Nelson Mandela."