Rami Malek was ''concerned'' about Charlie Hunnam ''staving'' while the worked on 'Papillon'.

The former 'Sons of Anarchy' star lost 35lbs to play a prisoner attempting to escape from a remote island in the upcoming drama, and his co-star admitted he was worried about how he would cope in such ''brutal circumstances.

Asked if he was worried about Charlie, Rami said: ''Yeah, how can I not be? I mean it's a very intense experience as it is. Filmmaking, and this one especially, it's not the glitz and glamour of Hollywood. We weren't out there going back to our trailers every two seconds.

''It's just out there sitting in the mud and hanging out and watching Charlie starve. So, I was a bit concerned, but he's alright.''

And this wasn't the first time Charlie, 38, dramatically lost weight as he'd only just regained the pounds he shed for 'The Lost City of Z'.

He explained to 'Entertainment Tonight': ''I did this two times in a row. I did a film called 'The Lost City of Z' and I lost 40 pounds for that exactly. I went from 185 to 145 exactly.

''I was down to 145 again for this, but I think I probably started at 180 so maybe [I lost] like 35 pounds.''

The 'King Arthur: Legend of the Sword' actor has often shot scenes topless on his movies but he admitted he's keen to cover up a bit more in the future.

He said: ''It's certainly not intentional and not something that I want to keep doing, but it seems to be a running theme. I don't know what that's about.''