Watercolors attributed to Adolf Hitler, painted when he was serving in the German army during World War One and then hidden away for more than 60 years, will be auctioned in southwest England on Tuesday.

The 21 paintings and sketches, the largest sale of Hitler's artwork for many years, has attracted huge interest and collectors from Russia, the United States and South Africa are expected to bid in the quiet Cornish town of Lostwithiel.

"People have been ringing up every day about it," said Ian Morris, auctioneer at Jefferys. "It's very unusual to have that number of Hitler's watercolors up for auction."

Questions have been raised about the provenance of the paintings and whether it is appropriate to auction the works of the mastermind of the Holocaust.

"There has been a minority of people who are unhappy," Morris told Reuters. "There are always people who have reservations about what's being sold."

The paintings of rural scenes on the border of Belgium and France were offered to Jefferys after the auctioneers sold a Hitler watercolor for 5,200 pounds ($9,790) in November 2005.

An elderly woman in Belgium, who wants to remain anonymous, contacted the company and offered for sale 21 works that had been found in the 1980s in an attic of a house near Huy.

Two refugees from France, apparently returning home, had left a sealed box there in 1919, a year after the end of the war.

The box contained the watercolors which depicted scenes around Le Quesnoy, the area in France where the women had originally come from.

The pictures were signed AH and Adolf Hitler. Hitler had spent "rest periods" near Le Quesnoy in the winters of 1916-17 and 1917-18, according to a historian asked to look into the provenance of the pictures.

An art consultant concluded in 1986 that the signatures appeared genuine although the standard of the paintings was not as high as previous Hitler work, perhaps due to "material and psychological conditions, including shock."

Jefferys, who have switched the sale from their showroom to a hotel in the town to allow more room for bidders, have catalogued the paintings as being "attributed to A. Hitler."

The Nazi leader showed artistic talent when he was a boy in Austria and wanted to be an artist. He was turned down twice by Vienna's Academy of Fine Arts but continued painting until the outbreak of war in 1914, and after he returned to civilian life.

Morris says he hopes one or two of the paintings will sell for more than £5,000 although he admits the standard of the work is not high.

"It is reasonable amateur art but not professional," he said.