Fans of actress Keira Knightley have the chance to snap up one of her designer gowns, which went up for auction in aid of Oxfam today.

The 21-year-old star of Pride and Prejudice and Bend It Like Beckham has donated the burgundy taffeta Vera Wang dress she wore at this year's Oscars ceremony to the Oxford-based charity.

It is being sold on online auction site eBay, with funds raised going to Oxfam's East African food crisis appeal, launched yesterday.

The appeal is the largest in the charity's 60-year history. Oxfam says the crisis is worse than the aftermath of the Indian Ocean tsunami and it has appealed to the public to donate £20m to help provide aid for people in Somalia, Kenya, Tanzania and Ethiopia, where more than 11m people are starving because of a major drought.

Ms Knightley said: "This is such an amazing dress and I'm really pleased to be able to donate it to Oxfam.

"I have seen the TV reports on the horrendous drought in East Africa and I know how desperate things have become, so I'm happy to be able to do something to help."

The dress was custom-made for the actress by Vera Wang, an American designer favoured by celebrities including Sharon Stone, Jennifer Lopez and Mariah Carey.

The draped, one-shoulder gown with 'flounce' will be an exhibit at the designer's shop in New York until the auction ends a week tomorrow.

Ms Knightley's role as Elizabeth Bennett in a film of Jane Austen's classic novel Pride and Prejudice won her an Academy Award nomination for best actress. She is dating actor Rupert Friend, 21, who played Mr Wickham in the film.

Mr Friend, whose mother lives in Stonesfield, near Witney, is a former member of Chipping Norton Youth Theatre and appeared in The Libertine with Johnny Depp, as well as Pride and Prejudice.