TOKYO/LOS ANGELES, Dec 25 (Reuters) - Sony Corp's Tokyo headquarters is changing its usual arm's-length relationship with its U.S. studio following a massive cyberattack and the controversy over the comedy "The Interview", with the group CEO being consulted on key decisions, company officials said.

Before the devastating cyberattack, Sony Pictures Entertainment was relatively independent of the Tokyo HQ, despite the company's slogan that it is "One Sony" across an empire of movies, music, gadgets and even insurance.

But group CEO Kazuo Hirai has become more involved after the hacking, which debilitated Sony Pictures' computer network and led to the online leaks of unreleased movies and embarrassing emails. It is considered the biggest attack of its kind on U.S. soil.

Officials with direct knowledge of the relationship said Sony Pictures Entertainment Chief Executive Michael Lynton consulted Hirai in his decision this week to push through with the release of the movie about a fictional plot to assassinate North Korean leader Kim Jong Un.

Lynton had made the call to drop the movie after major theatre chains cancelled plans to show it under threats from the hackers, the sources said. He reversed that decision less than a week later and released the movie after President Barack Obama joined other critics in saying Sony had erred, they said.

However, Hirai approved both decisions, the sources said.

"Lynton has been making the decisions but Hirai has been supporting them," one source said, declining to be named because he was not authorised to speak to media.

Hirai is now in California, where he has a house and spends his holidays, and is communicating frequently with Lynton, one official said.

The U.S. government blames North Korea for the attack, with Obama on Friday vowing a proportionate response and casting the issue as one of defending free speech and standing up to attempted "censorship" by "some dictator some place."

Ahead of the hastily scheduled premiere at some 320 independent theatres, Sony released the film straight to U.S. consumers on Wednesday in an unprecedented online debut after the hacker threats had prevented a wider Christmas release.

Hirai, 54, is bilingual in English and Japanese and grew up in the United States, Canada and Japan. After graduating from a Tokyo university, he joined Sony Music Entertainment Japan in 1984 and later worked for the company's video games unit where he was credited for growing its PlayStation business.

He is widely seen as one of the company's few executives capable of bringing together the manufacturing and movie-making cultures of Tokyo and Hollywood.