Germany is fighting to keep sealed the Eichmann files detailing the years the Holocaust’s chief logistics organiser spent on the run before he was captured by Mossad agents.

Those hoping to have a 50-year secrecy order overturned believe the government is embarrassed by details within that may prove German and Vatican officials colluded in his escape and freedom.

The secrecy order is being challenged in a benchmark court case against the BND, Germany’s domestic intelligence service, which wants the 4,500 pages of documents on Adolf Eichmann to remain out of the public domain. The service claims that intelligence agencies in other countries will be “frightened off” in future data-sharing if they are disclosed, Der Spiegel reported.

Critics believe this is a smokescreen designed to avoid official embarrassment both in Berlin and the Vatican. It is well documented that German Bishop Alois Hudal in Rome operated postwar “Ratlines,” getting passports for wanted Nazis to allow them to escape justice.

Franz Stangl, commandant of the Treblinka extermination camp, admitted to British Nazi expert Gitta Sereny that Hudal helped him get away after the Nazi defeat in 1945.

Eichmann also escaped. He was the ultimate “desk murderer” of the Third Reich who, as head of department IVB4 of the SS in Berlin, was responsible for the trains that carried millions to their deaths at extermination centres in Nazi occupied Poland.

After the war he was captured but fled from Allied custody. As the victors scoured Europe and the world for the top officials of the regime, Eichmann’s name was barely known: it was only as more and more details of the Holocaust emerged that his pivotal role in it began to dawn on Nazi hunters.

For 15 years he lived, sometimes under his own name, in Argentina, raising his family while working at a VW car plant. In 1960, acting on a tip-off, a Mossad team was despatched to Buenos Aires with orders to kidnap him and bring him back to Israel for trial. He was seized, stood trial, found guilty and hanged on May 31 1962.

Now the Federal Administrative Court in Leipzig, Germany, is studying the files about his getaway from Europe and life in Argentina to decide if they should be made public. The application for their release was made by German journalist Gabriele Weber.

The BND maintains that secrecy is necessary because “much of the information contained in the files was provided by an unnamed foreign intelligence service.” If released, the BND argues, it would “deter” other nations from sharing intelligence with Germany in the future.

But critics believe what the files will really reveal are the levels of assistance, succour and turning a blind eye to Nazi fugitives from officials in defeated Germany, together with details of Vatican assistance to top Nazis like him.

A decision on whether to release the files will be made in the next few weeks.