Pop diva Lady Gaga has denied she will appear in a much-publicised upcoming film about singer Dionne Warwick in which she was said to be set to play the soul legend's British "nemesis" Cilla Black.

Warwick appeared at the Cannes film festival Friday to promote the biopic, "Dionne", revealing that former Destiny's Child member LeToya Luckett would play her while Gaga would be Black, who died last year.

But Gaga's publicist immediately shot the idea down, telling the film industry bible Variety in comments published Saturday that she is "not attached to this project".

The casting had promoted much online speculation -- and hilarity -- over how the American singer would replicated Black's strong Liverpool "Scouse" accent.

The feud between the two 1960s stars dates back five decades to Warwick's fury at the way she claimed Black "copied" her vocal inflections on "Anyone Who Had A Heart".

Warwick's great standard also became a huge hit for Black in 1964.

Black "stole my music, and I was not a very happy camper about that", Warwick told reporters.

But the two did finally manage to bury the hatchet, Warwick said. "We grew up and understood each other. It all got cleared away."

Producers WW Film Company said it has already taken them 10 years to get the story -- based on Warwick's autobiography -- this far, and that shooting would begin in October.

It is not unusual for stars to be "attached" to projects launched at Cannes -- the world's most important film festival and market -- before final contracts are signed.