Simon Pegg has opened up about his battles with alcoholism and depression, saying: "I don’t think I would be here now if I hadn’t had help".

In an interview with The Guardian newspaper, the Mission: Impossible and Star Trek star said he had suffered from depression since he was 18 but used alcohol to self-medicate.

His alcoholism came to a head while he was shooting 2006's Mission: Impossible III in Los Angeles.

"When I watch that film back, I can see where I was then, which was fairly lost, and unhappy, and an alcoholic," he said.

Simon Pegg says he was "lost", "unhappy" and "an alcoholic" while filming Mission: Impossible III

Pegg says this was the start of his "crisis years". When he went to Comic-Con to promote his 2011 movie Paul he went missing for four days. The actor said that when he returned home to the UK he went into rehab which helped him turn his life around.

"I got into it. I got into the reasons I was feeling that way. I went into AA for a while, too", he said, adding: "I don’t think I would be here now if I hadn’t had help."

While he was in rehab, Pegg revealed that he was forced to get court orders to prevent newspaper stories being published. "They were sinking so low as to phoning up where I was and pretending to be my mother to get the story," he claimed.

The actor says that now he has recovered, he wants to tell that story. "I’m not ashamed of what happened", he said.

"And I think if anyone finds any relationship to it, then it might motivate them to get well. But I am not proud of it either – I don’t think it’s cool, like I was Mr. Rock’n’roll, blackout and all that sh*t. It wasn’t, it was just terrible."

Pegg rehabilitation conicided with the shooting of the sequel to Mission: Impossible III, 2011's Ghost Protocol, with the actor saying you can see his appearance improving as the movie progresses. "We always laugh about it when we watch the movie. Try it! You’ll be like: 'F***, he’s got cheekbones suddenly!'"

Simon Pegg in Mission: Impossible Ghost Protocol