Whale vomit found by a dog walker on a Welsh beach has sold at auction for £11,000.

The rare substance, known as ambergris, was found washed up on an Anglesey Beach by a walker.

Generally used to prolong the scent of perfume, the 1.1kg lump of rock was described as being foul-smelling by the auctioneers overseeing the unique sale.

They said they were “elated” over the sale to an anonymous French bidder who exceeded the anticipated price of £7,000.

“Somebody brought this smelly waxy rugby ball-shaped lump to us and asked us to sell it for them,” said Macclesfield auctioneer Adam Partridge.

"There are many things which can be mistaken for ambergris - fat, rubber and palm oil amongst others - but after doing some research and consulting the authorities on such things, we found out that what we had was indeed very valuable”.

He told the BBC: "We've had lots of unusual items pass through the doors over the years, but this is by far the weirdest."

Ambergris is formed inside whales’ stomach, as part of the digestive process, and is either passed as vomit or faeces. It is believed to be the first time such an item has been up for auction.