An $18bn (£10bn) lawsuit has been filed against Germany, accusing the country of making money by keeping artworks stolen from Holocaust victims.
Germany is accused of keeping art stolen from Holocaust victims
The legal action, by the Association of Holocaust Victims for Restitution of Artworks and Masterpieces (AHVRAM), is a first step against several countries.
Speaking outside the German finance ministry, lawyer Ed Fagan accused the government of retaining 2,000 artworks.
He said: "We are here because the thefts started here."
The civil action alleges that consecutive German governments from World War II to the present day have profited from artworks taken from Holocaust victims.
It names current finance minister Hans Eichel as a defendant.
The AHVRAM claims governments in Berlin benefited from trafficking in the stolen art, failed to take reasonable steps to find the true owners and did not give artworks back to Holocaust survivors' groups.
"It is not the business of government to steal or retain wrongly expropriated property," said Mr Fagan, a prominent US lawyer.
Austria, France and the US are also to be targeted by legal action on similar grounds, AHVRAM said.
'Owners not known'
A German government spokesman said the finance ministry took all legal action seriously but was waiting for the suit to be officially lodged.
"The German Government has already returned a million artworks and has only kept those whose owners are not known," he said.
The finance ministry confirmed it still owned works insured for a total of $73m (£40m).
The AHVRAM group contends the paintings should be sold and the proceeds given to Holocaust victims.
Mr Fagan is best known for achieving a $1.25bn (£700m) settlement from Swiss banks on behalf of Holocaust survivors.