Keira Knightley had no issues taking off her clothes for her latest film — it's becoming a habit.

"I always bare my breasts," the 23-year-old actress said, while promoting 'The Edge of Love'.

"It's not like it's only in this film!"

The 'Pirates of the Caribbean' star was seen naked in last year's 'Atonement'.

In the new wartime romance, which she was promoting at the Edinburgh International Film Festival on Wednesday, Knightley has an intimate scene with Cillian Murphy, who plays her onscreen husband.

"It was very simple. It was a sex scene and I never like them when they've got bras on."

So she had no problem when the director asked her to take off her bra.

"I said: 'All right then.'"

But it was a lot more difficult to convince Knightley to sing live in front of the cast, crew and some 100 extras.

"I thought I was going to die. My knees actually started buckling."