Actress Keira Knightley fears she's the worst friend in the world when she's on location, because she forgets to keep in touch with her pals.

The PIRATES OF THE CARIBBEAN star knew just how poor a pal she is when she realised she hadn't kept in touch with her best friend - while she was going through a romantic crisis.

Knightley explains, "I woke up one morning recently and realised I hadn't spoken to my best friend for a month-and-a-half.

"She had split up with her previous boyfriend and already gotten another one, and I didn't know about any of it.

"I'm not good with phones and I don't have email. I can't use a computer, so not being in touch is completely my fault.