Peter Morgan -- who scripted the films "Frost/Nixon" and "The Queen" -- is penning the untitled drama, which will focus on the years leading up to Queen's stellar performance at the 1985 Live Aid concert.
May confirmed that a film was in the pipeline.
"We have Peter Morgan on board, who's writing a script for this film, which will be about Freddie. I think we'll try and keep ourselves out of it as much as we can," he told BBC television.
Asked who was playing Mercury, he said: "We have Sacha Baron Cohen, which will probably be a shock to a lot of people, but he's been talking with us for a long time.
"He's been in on this project since we started talking about it seriously with Peter Morgan a couple of years ago. It's an amazing combination there."
Graham King, whose GK Films is developing the film with De Niro's Tribeca Productions, said: "Queen is one of the greatest rock bands of all time, and a music brand all unto itself.
"Freddie Mercury was an awe-inspiring performer, so with Sacha in the starring role, coupled with Peter's screenplay and the support of Queen, we have the perfect combination to tell the real story behind their success."
Queen -- Mercury, May, drummer Roger Taylor and bassist John Deacon -- are one of the world's best-selling bands.
The British rockers' hits include "Bohemian Rhapsody" (1975), "We Are the Champions" and "We Will Rock You" (1977), "Crazy Little Thing Called Love" (1979), "Another One Bites the Dust" (1980) and "These Are the Days of Our Lives" (1991).
Mercury died of AIDS-related pneumonia in 1991 at the age of 45.
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May confirmed that a film was in the pipeline.
"We have Peter Morgan on board, who's writing a script for this film, which will be about Freddie. I think we'll try and keep ourselves out of it as much as we can," he told BBC television.
Asked who was playing Mercury, he said: "We have Sacha Baron Cohen, which will probably be a shock to a lot of people, but he's been talking with us for a long time.
"He's been in on this project since we started talking about it seriously with Peter Morgan a couple of years ago. It's an amazing combination there."
Graham King, whose GK Films is developing the film with De Niro's Tribeca Productions, said: "Queen is one of the greatest rock bands of all time, and a music brand all unto itself.
"Freddie Mercury was an awe-inspiring performer, so with Sacha in the starring role, coupled with Peter's screenplay and the support of Queen, we have the perfect combination to tell the real story behind their success."
Queen -- Mercury, May, drummer Roger Taylor and bassist John Deacon -- are one of the world's best-selling bands.
The British rockers' hits include "Bohemian Rhapsody" (1975), "We Are the Champions" and "We Will Rock You" (1977), "Crazy Little Thing Called Love" (1979), "Another One Bites the Dust" (1980) and "These Are the Days of Our Lives" (1991).
Mercury died of AIDS-related pneumonia in 1991 at the age of 45.
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