Shia LaBeouf blames his erratic behaviour on method acting.

The 28-year-old star claims he was simply preparing for his role when he clashed with Alec Baldwin, 56, on the set of Broadway production 'Orphans', insisting this was also the case when he smacked actor Alan Cumming's backside at a performance of 'Cabaret'.

Speaking to Interview Magazine, LaBeouf explained: "Alec and I butted heads hard. I was sleeping in the park . . . At the time, I was out of my mind.

"My whole goal was to intimidate the f*** out of Baldwin. That was the role. And it wasn't going to be fake. I wanted him to be scared . . . So I went about doing that for three weeks of rehearsal."

LaBeouf - who starred in 'Lawless' and the 'Transformers' franchise - was arrested in June after drunkenly slapping Cumming and later spitting at a police officer.

He reflected: "I was reading about performance art of the '60s and '70s and so I thought . . . we're all involved here. It's not just your stage. We're all in here and we're all part of this. I was wrong."