LOS ANGELES • The Oscars have launched a landmark campaign to diversify the ranks of Academy Award voters who decide which actors, movies and film-makers earn recognition, but Hollywood's highest honours may remain a predominantly white affair for some time to come.

Amid an outcry against a field of Oscar-nominated performers lacking a single person of colour for a second straight year, the Academy of Motion Picture Arts and Sciences announced a sweeping affirmative action programme last Friday, pledging to double female and minority membership by 2020.

But host Chris Rock, an African-American, will not step away from the high-profile job, the show's producer Reginald Hudlin said last Saturday, telling Entertainment Tonight at an NAACP Image Awards luncheon that the comedian has scrapped his material. "As things got a little provocative and exciting, he said, 'I'm throwing out the show I wrote and writing a new show,'" Hudlin told ET. "You should expect (#OscarsSoWhite jokes)," Hudlin said. He added: "And, yes, the Academy is ready for him to do that."

The largely white, male and older makeup of the 6,000-plus film industry professionals who belong to the academy has long been cited as a barrier to racial and gender equality at the Oscars.

"It's unprecedented for the academy to make this kind of drastic overhaul," said Tom O'Neil, editor of the awards-tracking website Gold Derby. "It's a very dramatic announcement and a very welcome breakthrough."

The changes, unanimously approved last Thursday night by the academy's governing board, include a programme to "identify and recruit qualified new members who represent greater diversity" and to strip some older members of voting privileges.

Under the new rules, lifetime voting rights would be conferred only on those academy members who remain active in the film industry over the course of three 10-year terms or who have won or been nominated for an Oscar.

To increase diversity on the board of governors immediately, the Academy said it would establish three new governor seats that will be nominated by the president for three-year terms and confirmed by the board. It will involve new members on decisions about membership and governance, giving them a chance to become more active in decision-making and to help spot and nurture future leaders.

Actor Will Smith, film director Spike Lee and a handful of others had vowed to skip the Feb 28 awards show. They gave no indication that they plan to call off their Oscar boycott.

Last Friday, British actress Charlotte Rampling - nominated for Best Actress for 45 Years - waded into the row by saying Lee had been "racist to whites" in his criticism.

"You can never know for sure, but maybe black actors did not deserve to be in the final selection," she told Europe 1 radio, speaking in French.

She later clarified in a statement: "I regret that my comments could have been misinterpreted. I simply meant to say that in an ideal world, every performance will be given equal opportunities for consideration."

Warner Bros, one of Hollywood's major studios, issued a statement within hours of the Oscar announcement, embracing it, and Mr Kevin Tsujihara, chairman of the Time Warner Inc-owned studio, added: "There is more we must and will do."

None of the measures will affect voting for this year's Oscars race - a contest whose dearth of racial diversity led to the revival of the trending Twitter hashtag #OscarsSoWhite that emerged last year.

April Reign, an African- American activist who started the #OscarsSoWhite hashtag after last year's nominations, said she welcomed the changes outlined by the academy but was still calling on viewers to boycott the Oscars this year.

Longer-term change faces a deeply entrenched white, male- dominated system of studios, talent agencies and production companies that have been slow to welcome minorities in lead acting roles or as directors and screenwriters.

Women have long faced similar impediments. "The Oscar awards are the cosmetics of the industry. The infrastructure is the problem," said Mr Felix Sanchez, chairman of the National Hispanic Foundation for the Arts.

Last Saturday, Oscar-winning director Alejandro Gonzalez Inarritu, at a panel of producers nominated for awards by the Producers Guild of America, called the new academy rules "a great step" towards more diversity.

REUTERS, AGENCE FRANCE-PRESSE