Austria's Kronen Zeitung had reported that an early work by the celebrated Gustav Klimt had been found in a garage, after languishing unrecognised for years since being removed from the building where the Klimt brothers had a 19th century studio.

Art dealer Josef Renz, who has just bought the painting from a family living near the Austrian city of Linz, said the ceiling painting of a trumpet-playing cherub might have been done by the two brothers together if not by Gustav Klimt alone.

But Alfred Weidinger, art historian, Klimt specialist, and curator of the Schlossmuseum Belvedere in Vienna, told Reuters he recognised the painting as an early, historicist work by Ernst Klimt, who died in 1892, 26 years before Gustav.

"It's definitely not an important painting, even for Ernst Klimt," said Weidinger, noting that Ernst Klimt had died years before the Vienna Secession movement that rebelled against historicism and of which Gustav Klimt was a founding member.

Gustav Klimt, whose 150th birthday was on Saturday, is best known for his decorative, erotic paintings of the female body. His most famous work, The Kiss, was painted in 1907-8.

Renz disputed Weidinger's opinion of the rediscovered painting, telling Reuters: "It's definitely not only by Ernst. In the worst case scenario, it's by both brothers," adding that the two often worked together in the early years.

He declined to estimate the value of the painting, which he said was being assessed by experts and would then be restored and likely sold at auction in the autumn.

The experts agreed that the painting once adorned a stairwell in a Vienna building where the brothers shared a studio from 1883 to 1892. It was removed in the 1980s when a lift was installed in the building.

Renz said he had bought the painting from the family who found it in their garage. He said the family was in need of money and had no knowledge of the importance of the painting, but he had agreed to share profits from any auction with them.