A British peer is in Vienna to try to persuade Austrian authorities to return a £10m painting stolen from a British family by the Nazis.
Lord Janner wants British ministers to intervene
Lord Janner of Braunstone QC had earlier said Austrian authorities were being "disgraceful" by refusing to hand over the picture, painted by impressionist Egon Schiele.
The former Labour MP, a campaigner for the return of assets stolen by Adolf Hitler's regime, went to the Austrian Embassy in London to demand action.
The painting is currently held in Vienna's Leopold Gallery.
Lord Janner told BBC Radio 4's Today programme the painting had been left behind in Austria by a Jenny Steiner, a 74-year-old Jewish woman who fled the country when it united with Germany in 1938.
The Austrian Government passed a law in 1998 allowing the country's culture minister to authorise the return of looted art in public collections.
He said the Austrians were using a "cheating, fraudulent, disgraceful law" to keep the painting, saying it was a private matter.
"The Austrian law says that if items are owned by the state or are in state institutions then they must be returned," he said.
"But what they have done, very cleverly in this case, is to put them in an institution which is funded by the state, created by the state and where half the directors are appointed by the state and then said 'no, no, it's a private collection'.
Lord Janner has also asked the UK's Europe minister, Denis MacShane, to lobby the Austrian Government.
The painting, Hauser am Meer - or Houses on the Lake - was left behind when Ms Steiner fled Vienna to Paris.
She 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.
Steiner herself moved to Manhattan from Paris and died there in 1958 aged 95.
Another looted Schiele painting, Krumauer Landschaft (Stadt und Fluss), was sold at Sotheby's for £11.3m in June.