Underwear model Vanessa Perroncel, the ex-partner of Terry's England and former Chelsea team-mate Wayne Bridge, is at the heart of a media bidding war.
Clifford said yesterday he was in discussions with at least six media outlets all bidding for her side of the story.
A final decision on whether she will sell her story is yet to be made, but Clifford said the bidding offers could rise beyond the £250,000 mark.
Clifford said: "The £250,000 offer is just the latest bid. I am in negotiations on her behalf."
According to reports this morning the figure comes from a Sunday newspaper with talk of further magazine and TV interviews being arranged.
The amount is significant given the tough financial climate for some national newspapers.
The News of the World is believed to have paid a similar figure to Rebecca Loos for revelations about her affair with then England captain David Beckham in 2004.
In 2006, Tracey Temple sold her story about a two-year affair with deputy prime minister John Prescott with some reports suggesting the Mail on Sunday paid as much as £250,000 in a deal that was also brokered by Max Clifford.
The figure being offered to Perroncel dwarfs the £150,000 the Telegraph paid for the disc containing all the information that lead to last year's MP's expenses scandal.
Last night Perroncel was at Clifford's home, where she was being updated on the latest media offers.
The publicist told Sky News: "It's a story that everyone's talking about and it's a story that obviously all the papers and the television networks are very, very keen to get to the bottom of and find out what the truth is."
Clifford refused to be drawn on the veracity of the allegations but insisted some press claims were incorrect.
He said Perroncel had first to consider the welfare of her four-year-old son before she made a decision.
He told GMTV: "Obviously, she's just overwhelmed by what has happened".
"She has never spoken to a single journalist and she's all over all the papers with all kinds of allegations, some of which she said were true and some of which she said aren't true.
"She basically said 'What do I do? Journalists are knocking down my door; I've got people running round taking photos everywhere I go. I never sought this, I never asked for this, and I've never spoken to anybody'."
Asked whether there was any truth behind the alleged affair, he replied: "All I'm prepared to say is that she's known John a long time and obviously I think during that time they've become very close friends but anything more than that, I wouldn't want to say at this particular stage.
"It's really for her to decide what she wants to do."
England boss Fabio Capello was believed to be weighing up Terry's future as captain today.
Capello will have the final say on whether Terry can continue to lead the national team and he is expected to give his verdict well in advance of England's next match.
In the FA's first statement on the scandal, a spokesman said: "The FA confirms that England manager Fabio Capello alone will make the decision about John Terry's position.
"Fabio is fully up to speed with developments regarding John Terry.
"He spoke with our chairman Lord Triesman and chief executive Ian Watmore today, who both backed him to make the best decision for England on footballing grounds.
"Fabio is dealing with the matter in his own way using his extensive experience as a football manager."
Bridge, who has separated from Perroncel and now plays for Manchester City, said he did not intend to comment on the reports for the sake of the couple's son.
The allegations came to light after a breach of privacy injunction was lifted by Justice Tugendhat at the High Court in London on Friday.
Terry, who was voted Dad of the Year last year in a Daddies Sauce survey, has two children with his wife, who has now fled the family home and reportedly flown to Dubai with the children.
Terry, who has refused to comment on the allegations that he cheated on wife Toni, had been expected to lead England to this summer's World Cup in South Africa.
Chelsea manager Carlo Ancelotti confirmed that Terry would remain captain of the club but refused to discuss whether he should remain skipper of the national team.