They believe long-secret documents just uncovered in the United States show that at least pounds 1bn which should have been returned to Jews at the end of the Second World War is still secreted away in Switzerland.
Labour MP Greville Janner, who is chair of the Holocaust Education Trust and vice-president of the World Jewish Congress, said the papers are the first evidence of the whereabouts of the missing millions taken from Jewish families before and during the war.
They show there was a post-war deal between Switzerland and the Allies to split the proceeds of the Nazi accounts although it is unclear whether Switzerland handed the money over.
A five-page paper produced in 1946 by the Allies estimated there was $400m (pounds 260m) - at least $4bn at today's prices - of Nazi gold in Swiss banks and it was "perfectly possible" all of it was looted. British intelligence was concerned about Nazis using Swiss banks as early as October 1941 and in January 1942 the British embassy in Washington detailed movements of 21 tons of gold from Berlin to Berne.
Mr Janner said: "It is an absolute certainty that there is a huge amount of money still in Swiss banks that doesn't belong to them. The interest must amount to multi-millions. This was Nazi loot taken from murdered people."
The development is the latest twist in decades of efforts by Jewish organisations to find out what happened to tons of gold which they claim the Nazis stole.
Previous appeals by Mr Janner to the Government for information have drawn a blank. Last month, Malcolm Rifkind, the Foreign Secretary, said they knew nothing about documents concerning the funds deposited by the Nazis. "None of the intelligence agencies is aware of having such information," he said.
But after the papers were uncovered by the Holocaust Education Trust in America, Mr Rifkind yesterday promised to make further inquiries.
Mr Janner said they needed to see the Government's papers from the time to pursue the matter and said the previous failure to find evidence was "either culpable negligence or a cover-up".
In the recently de-classified documents from the US national archives, the paper dated 2 February 1946 on Allied claims against the Swiss "for the return of looted gold" laid out detailed figures. It said even allowing for all possible non-looted gold available to the Germans there was a minimum of $185m of gold which must have been looted. A "fair assumption" was $289m which was recommended as a "reasonable settlement" for the Swiss government to hand to the Allies.Reuse content