Tearful Douglas thanks director Soderbergh for Liberace

Douglas got emotional when talking about the film

Film star Michael Douglas broke down in tears at a news conference in Cannes while discussing his role as flamboyant pianist Liberace.

He stars in the film - directed by Steven Soderbergh - with Matt Damon, who plays his secret lover.

A visibly upset Douglas said Behind the Candelabra, in competition at Cannes, held special meaning as it began life "right after my cancer".

He called the film "a beautiful gift", as he thanked Soderbergh and Damon.

"I will be eternally grateful," he said to applause from the gathered media.

Douglas, who won an Oscar in 1988 for his role as Gordon Gekko in Wall Street, underwent treatment for a form of throat cancer after being diagnosed in 2010.

The film, based on a book by Liberace's former lover Scott Thorson, shows the pair's often stormy relationship as the pianist - one of the most popular entertainers in the US - shielded his sexuality from the public.

Douglas said director Soderbergh initially approached him with the idea on the set of the film Traffic.

"I thought he was messing with me," said Douglas. "I was playing a drug tsar in this movie and I saw this pensive look on Steven's face and he said, 'Have you ever thought about Liberace?'

"I said, 'What does that have to do with anything?' and we teased each other about it. I tried to do a take-off of his voice and forgot all about it.

"Then, seven years later, he got his outlet, I guess, with Scott's book. He was the love of Lee's life."

The film has been made outside the studio system with US cable broadcaster HBO, amid reports that the gay subject matter had put off studio heads.

Douglas played the reports down, saying: "It's a difficult time for smaller independent pictures. Things seem to still be led by gambling on very large-budget movies with large marketing budgets.

"I don't think the problem they had was with the gay issue, it was that they don't like to be bothered with smaller pictures."

But Soderbergh added: "The feeling was, when we first went round with this movie four or five years ago, the sense we got was, 'We're not convinced there's an audience for this movie except for people who are gay'."

He said he looked forward to a time "when it just isn't an issue".

Douglas and Damon star in Behind the Candelabra about the pianist Liberace and his secret lover Scott Thorson

Damon, who worked with Soderbergh in the Ocean's 11 series, shares several intimate scenes with Douglas and joked that he now had something in common with actresses Sharon Stone, Glenn Close and Demi Moore - who have all had bedroom scenes with Douglas.

"We can all go out and swap stories now," he joked.

Soderbergh also confirmed reports that the film would be his last for the near future.

"I came here 24 years ago," he said. "I'm absolutely taking a break. I don't know how extended it will be but I can't say that if this were the last movie I made, I'd be unhappy. I'm really proud of this film.

"It's been a nice ride."