Lord Janner wants British ministers to intervene

The painting, by 20th Century Austrian expressionist Egon Schiele, is valued at �10m ($15m) and is currently in the collection of a Vienna gallery.

But there is a dispute over whether the gallery is bound by an Austrian law that allows the return of looted artworks.

The family's case has been taken up by Lord Janner of Braunstone, QC, who described the Austrian stance as "a fraud" and "disgraceful".

Nazi auction

Lord Janner has asked the UK's Europe Minister, Denis MacShane, to lobby the Austrian Government.

The peer told BBC News Online: "The painting was stolen from Jenny Steiner, whose family now live in the UK."

"I'm asking [the British Government] to intervene on behalf of British citizens."

He is also hoping to meet the Austrian ambassador to London on Tuesday.

The painting, Hauser am Meer - or Houses on the Lake - originally belonged to Jenny Steiner, a Jewish friend of Schiele who was forced to flee Vienna in 1938, aged 74.

She went to Paris and asked her maid to forward her belongings - but much, including the painting - was confiscated by the Nazis and sold at auction.

Steiner's daughter, Anna Weinberg, meanwhile, moved to the UK.

'Public gallery'

The Austrian Government passed a law in 1998 allowing the country's culture minister to authorise the return of looted art in public collections.

But the Leopold Museum in Vienna, which owns Hauser am Meer, says it is a private gallery and so is not bound by the law.

But the family say it is funded by public money and half its directors are appointed by the government.

"They are trying to avoid returning this painting because they say the gallery is a private one," Lord Janner said.

Another looted Schiele painting, Krumauer Landschaft (Stadt und Fluss), was sold at Sotheby's for �11.3m in June.

Past controversy

The Leopold Museum said they would have to consult experts before commenting.

The gallery's collection has been in the spotlight before when two Schiele paintings were seized by US authorities while on loan to the Museum of Modern Art in New York in1998.

But the US Supreme Court later ruled that they had been wrongly seized.

Jewish families said the paintings had been looted from their relatives by Nazis.