"This is very disappointing," said Polanski's lawyer, Harland Braun.

In a letter to the academy, Braun threatened to file suit, writing that the academy has failed to follow its own rules by not allowing Polanski a chance to defend himself. "We are not here contesting the merits of the expulsion decision, but rather your organization's blatant disregard of its own standards of conduct in, as well as its violations of the standards required by California corporations code,” Braun wrote, according to the Los Angeles Times.

The Academy voted last week to expel the 84-year-old Oscar-winning director of "The Pianist" along with actor Bill Cosby in light of sexual assault cases against both men.

The decision had been reached on the heels of Cosby's conviction for drugging and sexually assaulting a woman in 2004, for which he faces 30 years in prison. He is appealing the conviction.

'A total misunderstanding and harassment'

Polanski, who fled the United States after pleading guilty to having unlawful sex with a 13-year-old girl in Los Angeles in 1977 after plying her with champagne and Quaaludes, called the decision last week "the height of hypocrisy," according to his lawyer Jan Olszewski. Comparing Polanski to Cosby, Olszewski said, was "a total misunderstanding and harassment."

Read more: New investigation into Roman Polanski over sex crime allegations

Polanski has been one of the more divisive members of the organization for years.

His expulsion comes after Harvey Weinstein's removal  following extensive sexual assault allegations, upon which the academy adopted a code of conduct. Put in place in December, the code reads that the organization has no place for "people who abuse their status, power or influence in a manner that violates standards of decency." It allows for the academy's board to suspend or expel those who "comprise the integrity" of the academy.

Read more: NYT investigation on Harvey Weinstein to become a film 

Polanski sees #MeToo as 'mass hysteria'

The allegations against Weinstein, revealed in ground-breaking investigative reporting in the New Yorker and The New York Times, kicked off the #MeToo movement, which has brought intense scrutiny to Hollywood and the academy.

In an interview with Polish media before the expulsion, Polanski dismissed the #MeToo movement as "mass hysteria" and "hypocrisy."

Read more: Polanski dodges investigation into teen rape in Switzerland

Asked what he thinks of the movie industry's recent reckoning with sexual harassment, Polanski told this week's edition of Newsweek Polska: "I think this is the kind of mass hysteria that occurs in society from time to time."

"Sometimes it's very dramatic, like the French Revolution or the St Bartholomew's Day massacre in France, or sometimes it's less bloody, like 1968 in Poland or McCarthyism in the US," he added.

"Everyone is trying to back this movement, mainly out of fear... I think it's total hypocrisy."

Polanski, who holds dual citizenship with France and Poland and currently lives in France, is wanted in the US for the 1977 rape of Samantha Geimer. He has for years sought to negotiate a deal in the case with US authorities.

Geimer, who has said in the past that she has forgiven Polanski, dismissed the Academy's move to expel him as "an ugly and cruel action which serves only appearance."

Read more: US judge rejects Roman Polanski victim's bid to close case

In its statement, the film academy said its board "continues to encourage ethical standards that require members to uphold the Academy's values of respect for human dignity."

ct/eg (AP, AFP, dpa)