AMERICAN Deontay Wilder has agreed terms to fight Anthony Joshua in Britain later this year in a bout that would crown the first undisputed heavyweight champion since 2000.

Briton Joshua (21-0) is the holder of the IBF, WBA, WBO and IBO titles while Wilder (40-0) is the WBC world champion.

Wilder's co-manager Shelly Finkel said on Tuesday they had agreed to the latest terms offered by Joshua's promoter Eddie Hearn.

"We have agreed to the terms that Eddie has put out to us for a fight in the UK. Deontay has accepted his terms to fight in the UK," Finkel said.

Wilder, in a message posted on his Twitter account, confirmed he had agreed to fight in Britain but said an offer to Joshua of $US50 million ($A65 million) to fight in the United States was still on the table.

"The $50M offer for him to fight me next in the US is still available," Wilder said.

"Today I even agreed to their offer to fight Joshua next in the UK. If he prefers the fight in the UK, the ball is in their court."

The WBC title is the only one remaining on Joshua's radar after he added the WBO championship to his collection by defeating New Zealand's previously unbeaten Joseph Parker in March by unanimous decision.