Leading members of Germany's foreign ministry were deeply involved in the Holocaust, according to an official report published yesterday which blew apart decades of diplomats' denial they had played an important role in the mass murder of European Jews.

Senior officials were willing participants in the Nazi campaign rather than representing a focus of opposition to the Third Reich, visiting Dachau concentration camp for training before the second world war, helping to organise the killing of Jews during the conflict and protecting convicted war criminals from travelling to countries where they might be arrested after the war.

"The German foreign ministry collaborated with the Nazis' violent politics and especially assisted in all aspects of the discrimination, deportation, persecution and genocide of the Jews," said Eckhart Conze, of Marburg university, one of four historians who helped prepare the official report on the ministry's involvement in the Holocaust. Former foreign minister Joschka Fischer commissioned the study while in office in 2005, following a public debate over the ministry's Nazi past, with the ministry still publishing positive obituaries about former employees who were committed Nazis.

The 900-page report, called The Office and the Past: German Diplomats in the Third Reich and the Federal Republic, went on sale in bookstores yesterday and will be officially handed over to the current foreign minister Guido Westerwelle on Thursday. On Sunday, Westerwelle told German television station ARD he was thinking of making it mandatory reading material for all future diplomats.

The historians researched 32 different archives worldwide and chased material they found in dozens of interviews with eyewitnesses, to offer a starkly different picture from that painted by the foreign ministry for years.

In an interview with the Associated Press news agency, Conze said that documents indicated Franz Rademacher, head of the ministry's so-called Jew department, travelled to Serbia during the Third Reich to help organise the killing of Jews in eastern Europe.

The historians found Rademacher's travel expenses from a trip to Serbia in October 1941 which he had titled "liquidation of Jews in Belgrade". This was one of many documents the historians said showed employees actively supported the Nazis' efforts.

The report noted young foreign ministry attaches were made to visit Dachau concentration camp in Bavaria as part of their training up until the outbreak of war in 1939.

Though mass extermination of Jews had not begun then, the historians concluded the mandatory concentration camp visits would have set an anti-Semitic tone within the ministry. Similar indoctrination by the Nazis was also carried out at other ministries, the police and the courts to help create an ideologically uniform elite.

The historians said the ministry had re-employed known Nazis immediately after the war, some having successful careers in West Germany. "Even in the 1950s and 1960s, convicted war criminals were warned again and again by foreign office staffers to not travel to certain countries where they might have been arrested," Conze said.