Eva Mendes and Penelope Cruz both up for Callas

The Spanish actress Penelope Cruz, about to open in the musical movie Nine opposite Daniel Day-Lewis, is reported to be in talks to play the great soprano Maria Callas in a British movie due to be filmed next year. But she could be beaten to the big screen by the American Eva Mendes, playing the same role in another similar production.

Callas is to be made by Future Films based on the best-selling biography So Proud, So Fragile by the Italian author Alfonso Signorini. As well as Cruz, the American actress Anne Hathaway (The Devil Wears Prada, Rachel Getting Married) is also said to be a contender for the lead role.

It is understood the film will concentrate on Callas's fiery relationship with Aristotle Onassis, the Greek shipping magnate who, following the opera singer's death, went on to marry JFK's widow, Jackie Kennedy.

Maria Callas - known popularly during her lifetime as La Divina - had one of the most beautiful soprano voices ever heard. But her career was not easy, says producer Stephen Margolis.

"She had to struggle not only with myopia that left her almost blind on stage, but also to compete with her great rival, the Italian soprano Renata Tebaldi," Margolis told the Observer. "The two singers were pitted against each other constantly."

Like Callas, Future Films also face competition. The other project is Greek Fire, based on the biography of the same name by the Greek-American writer Nicholas Gage (not to be confused with Cage). The English actor-screenwriter Julian Fellowes is writing the screenplay and Eva Mendes is set to star.