The Guardian said Whishaw, who was recently seen in the film "Skyfall," was the band Queen's first choice to play lead singer Mercury in a movie.
Sacha Baron Cohen was initially attached to the role, but left the project due to creative differences with the surviving members of Queen.
The as-yet-untitled film about the band's formative years leading up to its memorable 1985 Live Aid performance is to go into production next year, the newspaper said.
Mercury died in 1991 of AIDS-related illness.
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