Foreman has not fought since losing to Shannon Briggs in 1997

Promoter Don King has said that Foreman has made a verbal commitment on a $20m return to the ring at the age of 55.

But the boxer told Houston TV station KRIV: "Everyone thinks it's a verbal commitment when I smile.

"I'm not going to say anyone's got a contract with me right now. It has to be in writing and when it happens, I'm going to make an announcement myself."

Foreman added: "There's a chance that I even may promote the whole thing myself."

King said he had spoken to Foreman about the prospects of a fight.

"We've got a verbal deal," King said last week. "He said, 'I'm willing to fight one more time'."

King said no opponent, date or location have been set, although Foreman said last week he'd like any fight to be in his hometown of Houston.

Foreman said he would not make a deal until his weight gets down to 225lbs (102kg).

He acknowledged that several promoters are trying to work out a deal with him as attempts to make a comeback to mark the 30th anniversary of his title loss to Muhammad Ali.