Ludwigsburg, Germany (dpa) - Germany's war crimes prosecutor issued an impassioned warning Thursday against any further delay in bringing 88-year-old John Demjanjuk to trial for allegedly helping kill 29,000 Jews at a Nazi death camp.

Kurt Schrimm, who heads Germany's national office on war crimes in Ludwigsburg, said his staff have already set out a compelling case against Demjanjuk, a Ukrainian-born man who now lives in the US state of Ohio. Schrimm rejected claims by local German prosecutors that the case was incomplete.

Demjanjuk was acquitted in 1993 by the Israeli Supreme Court of charges that he was a guard at the Treblinka death camp.

The Germans say they have proof that he served the Nazis from April to July 1943 at a different extermination camp, Sobibor, operating diesel engines that were used to gas inmates to death.

"The evidence we have sent to Munich suffices," Schrimm told Deutsche Presse-Agentur dpa.

He said a failure to try Demjanjuk would prompt fresh criticism of the German justice authorities.

Schrimm's unit does not have the powers to prosecute Demjanjuk itself. Insted it sent the file to prosecutors in Munich last November. Munich is the German city where Demjanjuk lived as a displaced person till he emigrated to the United States in 1952.

The Schrimm team found a Sobibor witness and obtained expert evidence that Demjanjuk's Nazi identity card was genuine and had not been tampered with by Soviet authorities. Schrimm then hoped Munich would apply quickly for Demjanjuk's extradition.

However Munich has initiated a new forensic study at the Bavarian police laboratories into the SS identity card, which links Demjanjuk to the so-called Trawniki group of Ukrainian and Baltic "volunteers" who were recruited to do some of the Nazis' dirty work.

"The card has been thoroughly checked by three US experts. It is genuine without a shadow of a doubt," said Schrimm, who also criticized Munich for asking Ukraine, Poland, Israel and the United States for any extra evidence they might have.

"We sent sent 17 binders of evidence to Munich," he said. "It was the result of comprehensive research. Every known document connected to the name Demjanjuk is already in there as an original or a copy."

"There is an adequate case there to bring to trial."

Schrimm said eastern European nations were generally slow to respond to calls for assistance in inquiries.

"The world can't wait. Demjanjuk is old. Every day counts now," he said.

Eli Rosenbaum, head of the US Office of Special Investigations (OSI), has a vital interest in seeing Demjanjuk brought to justice.

The acquittal on the Treblinka charges was a serious setback to the OSI, which helped compile the case that he was a Treblinka guard remembered by the nickname "Ivan the Terrible." That claim will not be part of the German case.

But the OSI did find enough evidence of SS membership to have Demjanjuk formally stripped of his US citizenship in 2008.

In Munich Thursday, a prosecutions spokesman defended the re-examination of the evidence. He said it was not in the interest of the Munich prosecutions department to risk another acquittal.

"We are used to doing a proper job, and aim to avoid evidentiary problems cropping up at trial that might have been avoided in advance," he said. He also defended the bid to find any further Sobibor survivors in Israel as witnesses.

The identity card indicating Demjanjuk was in the SS paramilitary group which worked in the death camps was a key to his conviction by an Israeli court in 1988, which was overturned on appeal.

The certificate contains the Ukrainian's photograph, an SS service number and notes about his service at two Nazi sites.

Claims that the abbreviation SS might have been added later or the photograph might have been switched are ruled out by Schrimm's experts, who say both those elements are demonstrably original.