Sony's Japanese CEO Kazuo Hirai intervened, insisting a scene was made less gratuitous (AFP/Getty) / AFP/Getty

Speaking at CES 2015, Kazuo Hirai called the attack “vicious and malicious”

Sony’s boss has slammed the huge cyber-attack that crippled the company’s film division, saying his employees were the victims of a "vicious and malicious cyberattack" and adding that he was proud of them for standing against "the extortionist efforts of criminals".

Kazuo Hirai, Sony’s CEO, has not previously spoken about the hack. But he opened a press event at the Consumer Electronics Show in Las Vegas by saying that he had to address the controversy.

The attack began in late November and left Sony systems crippled for weeks. The FBI has blamed the hack on North Korea — and said the film was a response to Sony’s plan to release The Interview — though many security experts have cast doubt on that belief.

Mr Hirai did not offer any new information about the hack, but said that freedom of speech and expression are "very important" to Sony and its entertainment business.

He went on to thank the telecommunications and internet companies which helped with the release, and "most importantly the people who have gone out to see the movie in theatres or through various online venues".

He also joked about another Sony film release, saying: "By the way, Annie is also a great movie as well."

Sony executives spent most of the CES event talking about new televisions, high-resolution cameras and other electronic gadgets that the company is introducing this year.

Additional reporting by Press Association