Britain released “hundreds” of suspected Nazi war criminals after the Holocaust, according to a leading historian.

Dan Plesch uncovered United Nations War Crimes Commission documents which prove that former Nazi officers — including the “Bookkeeper of Auschwitz” Oskar Gröning , who was jailed for four years earlier this month — were released by the UK after the Second World War.

Dr Plesch, director of the Centre for International Studies and Diplomacy at Soas, University of London, discovered that the UK freed the Nazis under pressure from the US, which was keen to recruit Germany as a new ally in the Cold War against the Soviet Union.

Dr Plesch, who said Britain also released notorious Nazis Erich von Manstein, Gerd von Rundstedt and Albert Kesselring, explained: “There was a political argument at the time in which those opposed to international criminal justice succeeded… There were lots of people who were either released without much investigation — and then there were people who were actually in prison camps and let out.

“Hundreds of suspects and convicted Nazis [were released].

“Indeed, British jails were empty by 1957 after much pressure from Germany and German army veterans associations who refused to support rearmament against the USSR while they remained in jail.”

Dr Plesch, who is preparing a new book on this subject, said governments today should learn from these mistakes and investigate war crime claims against countries such as Israel and Syria.

He argued that a refusal to deal with international law “led to the suppression of attempts to hold the Nazis to account.

“These are very important lessons for our own time… states, including Israel, need to give much more serious attention to the importance of international criminal law today.”