Britney Spears' half-eaten sandwich has sold for over $500 in an internet auction.

The seller, who goes by the user name of 'derrickito', posted the egg salad sandwich on the Australian version of eBay along with a corn dog supposedly nibbled by the pop star's husband Kevin Federline.

Forty-three bids were placed for the vacuum-sealed savoury treats before online gaming company Golden Palace Casino purchased both items for 520 Australian dollars.

A spokesman for the company, which already owns an interesting collection of Britney "memorabilia", said: "With her saliva and urine already securely in their possession, the casino might even be able to clone Britney pretty soon."

'Derrickito' claims to have been working as a waiter at a music awards ceremony at a "fancy schmancy" New York hotel when he swiped the goodies.

The quick-thinking seller then carefully packaged the leftovers and posted them on eBay.

'Derrickito' explains Britney ate one half of her "egg salad sandwich with tomato and lettuce on wheat bread" and took a couple of bites from the other half.

He added: "Kevin Federline had a few things to eat that night, but the only leftover item I managed to pick up from him was a corn dog.

"Later, I went to clear their plates with it, and as I was picking up the plate Britney picked it up really quick, giggled, and said, 'I can't let that go to waste' and quickly took a big bite off of the stick end of the corn dog."