The dress has gone on display in Oxfam's Notting Hill shop in London

The UK size 6, Vera Wang designed claret-coloured taffeta gown is being sold to the highest bidder on internet auction site ebay for Oxfam.

Currently bids have reached �3,800, with the auction due to end at 1700 BST on Monday.

Proceeds will aid the charity's �20m appeal for drought-hit East Africa.

Knightley's role in a remake of Pride and Prejudice gained her an Academy Award nomination for best actress but the dress she wore on the red carpet also won her many plaudits.

The 21-year-old star approached the charity herself with the gift.

The dress could raise enough to feed 500 children for 30 days

Oxfam said the last few minutes of the auction was likely to see a flurry of bids.

If the custom-made dress raised �5,000 it would provide enough food to help feed 500 children for 30 days, it said.

Oxfam spokeswoman Katie Abbotts said: "We are expecting the last half an hour to be busy as that is when the big bidders will come in potentially.

"We are absolutely delighted that we have had such generous bids so far for what was an amazing donation.

"But with just under 24 hours to go we genuinely hope that it will double or triple or even quadruple because this money is being raised for a very important reason."

After donating the dress, Knightley said: "This is such an amazing dress and I am really pleased to be able to donate it to Oxfam.