Green Day frontman Billie Joe Armstrong has broken his silence about the substance abuse issues that drove him to rehab last year (12), revealing his infamous outburst at the iHeartRadio festival in Las Vegas last September (12) made him realise it was time to get help.

The American Idiot singer has recalled his darkest days in a new Rolling Stone magazine interview, explaining years of alcohol and prescription pill abuse took their toll on his health.

He explains, "I couldn't predict where I was going to end up at the end of the night. I'd wake up in a strange house on a couch. I wouldn't remember how. It was a complete blackout."

But it was his behaviour at the Las Vegas festival, where he hurled abuse at promoters and smashed up his guitar onstage after accusing them of cutting his band's set short, which was the catalyst for him seeking professional treatment.

He adds, "I remember tiny things. The next morning, I woke up. I asked (wife) Adrienne, 'How bad was it?' She said, 'It's bad'. I called my manager and he said, 'You're getting on a plane, going back to Oakland (California) and going into rehab immediately.'"

Armstrong has been out of the public eye ever since, prompting his bandmates to scrap a series of concerts and appearances to promote their album trilogy Uno!, Dos! and Tre!

The rockers will pick up tour dates next month (Mar13) and make their debut at the South By Southwest festival in Austin, Texas.