Hitler is thought to have produced them while serving in the German army during the first world war.

The collection of paintings and sketches was found in an attic in Belgium.

Chris Walton, a spokesman for Jefferys Auctioneers, said on Tuesday the 21 watercolours and two sketches, sold individually for prices from $6,100 to $19,975.

Many of the paintings, which were mostly landscapes, were signed "A Hitler", while others were signed "AH".

Ian Morris, the auctioneer, said that few of the successful bidders were prepared to be identified or to speak to journalists.

He said: "There may be a stigma attached to buying Hitler art."

One bidder - who refused to identify himself but confirmed he was an Estonian acting on behalf of an Eastern European businessman - said he had successfully purchased artwork.

He said: "I think they are probably being bought for business - the paintings are not very good and it's not nice to have a 'Hitler' on your living room wall."

Comic gatecrashers

The auction was gatecrashed by Aaron Barschak - a comic who gained notoriety in 2003 when he evaded security at Prince William's birthday party at Windsor Castle and climbed on stage dressed as Osama bin Laden - and Peter Cunningham, who dressed as Hitler.

As security guards dragged them out, Barschak shouted: "See - they're throwing Jews out."
  
Barschak's wife said that her husband and Cunningham had considered the sale offensive.

She said: "It's not a surprise that when they did decide to hold it, they chose a quiet village in Cornwall.

"If it was in London there would have been protests. Adolf Hitler was a mass murderer and to make money from that is wrong."

Controversial

Walton said: "Some people would consider the sale somewhat controversial, but the pieces were executed so long ago - nearly 100 years ago - that they now just represent something of the past."

Hitler is thought to have painted hundreds of pieces before becoming leader of the Nazi party. In the past, his paintings have sold for between $5,000 and $50,000.

In many European countries, including Germany, it is illegal to buy, own or sell Nazi memorabilia.

A German auction house in 2001 withdrew a Hitler painting following public protests.

The Centre of Military History in Washington has hundreds of Nazi-related pieces - including four Hitler paintings - but they are not on display.