Files detailing gold the Nazis looted from Auschwitz and other death camp victims disappeared without trace and were possibly destroyed as late as the 1970s, according to an official report obtained by Reuters on Wednesday.

The report was compiled by Germany's Federal Archive, with help from the Bundesbank, after Washington asked Bonn to shed more light on recent revelations about the Nazis' wartime gold trade, a spokeswoman for the Interior Ministry said.It was due to be released in the next few weeks, she said.

The 26 lost folders, known as the Melmer files after the SS officer responsible for tallying up how much gold was plundered from Jews exterminated in concentration camps, could have provided a basis for Holocaust victims' claims for damages against German and Swiss banks.

Their disappearance could be an embarrassment to the German government and a setback to its postwar efforts to come to terms with its Nazi legacy.

"With increasing displeasure it became clear that the 26 Melmer folders that were not microfilmed had disappeared without trace," the report concludes.

"It is assumed that these included the incoming and delivery bookings for jewelry, other valuables and dental gold which were delivered from Auschwitz (death camp) in 76 consignments to Berlin."

The report said the investigation into the missing files was launched last year after it emerged from U.S. archives that Allies authorities confiscated them at the end of World War II and handed them in 1948 to the Bank Deutscher Laender, the precursor to the Bundesbank central bank, for safe-keeping.

The looted gold was booked into the Reichsbank, Nazi Germany's central bank, in a further 50 account books which were also confiscated but then returned to West German authorities.

Victims' gold was booked in along with millions of dollars worth of gold ingots plundered from banks in Nazi-occupied countries and sold, much of it in Switzerland, to raise hard currency to buy metals for arms manufacture.

Some of the books were microfilmed - and fragments of these have been found in the Bundesbank archive and Federal Archive. The Allies made no copies of the Melmer files - only a few pages of which have survived as they were included in the books.

"The result is disappointing," the report said.

"The (Reichsbank) precious metals department documents were split up by the Bank Deutscher Laender administration and/or the Reichsbank's liquidator, which took charge of all or a large part of them in 1955," it said.

"They were possibly destroyed along with the liquidator's receipts after 1976, to the extent that they were still present at that time."

The report said many questions remained unanswered.

The role of Albert Thoms, the chief of the Reichsbank precious metals department who was later made a top official in the Bank Deutscher Laender by the Allies, was still unclear, the report said. Thoms died in 1977 and several missing documents were found among his papers, it said.

It also mentioned the last liquidator of the Reichsbank, Ulrich Benckert, 86, who apparently in 1975 had copies of receipts of gold delivered from camps. The copies had gone missing by the following year.

The report said he was too ill to be questioned.