No ethnic minority actors or actresses were nominated for the top Oscar awards for the second year running, sparking an outcry and prompting the Academy of Motion Picture Arts and Sciences to announce reforms.
McKellen, 76, who is gay and a co-founder of the rights group Stonewall, said he sympathised with people who have felt under-represented in the industry.
"I think you have to live in Hollywood, where the Oscars mean so much more than they do elsewhere, to understand why people's feelings are running so high," McKellen said.
"And it's a legitimate complaint and the Oscars has become the focus of those worries, so I sympathise."
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The all-white nominations sparked debate in the film industry and a social media campaign under the hashtag #OscarsSoWhite.
In response the Academy board announced it would double the number of women and people from minority backgrounds among its members, who vote for Oscar nominees and winners.
McKellen made the comments at the launch of a programme about William Shakespeare and film at the British Film Institute in London, to mark 400 years since the playwright's death.
McKellen will also host public bus tours to iconic locations shown in the film.