Mariah Carey signs on for The Butler - report

Mariah Carey has reportedly signed on to join the all-star cast of biopic The Butler.

The diva will reteam with her Precious director Lee Daniels for the project, which chronicles the life of manservant Eugene Allen, who served under eight US presidents.

It is not known what role Carey will have in the film, which will star Forest Whitaker as Allen and Oprah Winfrey as his wife. Also joining the cast: James Marsden as John F. Kennedy, Minka Kelly as Jackie Kennedy, John Cusack as Richard Nixon and Alan Rickman and Jane Fonda as Ronald and Nancy Reagan.

The casting news comes just two days after Carey confirmed reports she has signed on as the new judge on TV talent show American Idol.

Filming on The Butler has begun in New Orleans, Louisiana.