Charlize Theron has a stern message for journalists who interview her at press junkets - ‘Do your homework!’ The Oscar winner admits she’s often left offended by comments reporters make when they chat to her about films in press conference-style promotional interviews.

And the stunning star is tired of questions about her plainer characters in films like Monster, North Country, In The Valley of Elah and her new film Sleepwalking.

She says, "It bothers me that if you’re gonna come in, especially to these junkets… and you’re gonna be covering this industry, you should go and do your homework a little bit.

"I understand that there’s a sense of entertainment and everybody wants the quick soundbite, but, at the same time, especially when you’re dealing with material that’s serious… Don’t come to me and tell me that North Country was a transformation; it’s dirt on my face.

"I got to a point… where somebody (said)… ‘You love playing ugly people…’ and I take such offence to that.

"Part of me almost wants to go, ‘Y’know what, that’s actually me… with no make-up, and I’m somewhat offended right now because you’re basically saying I’m ugly.’"