Declassified account shows Britain would have preferred to see Nazi leaders executed or imprisoned at end of second world war

The British government opposed the establishment of the Nuremberg war crimes tribunals at the end of the second world war because it wanted selected Nazi leaders to be summarily executed and others to be imprisoned without trial, according to a contemporary account that is declassified on Friday.

Winston Churchill made the proposal at the "Big Three" conference at Yalta in February 1945, according to the account, but was overruled by Franklin D Roosevelt, who believed the US public would demand proper trials, and Joseph Stalin, who argued that public trials possessed excellent propaganda value.

The British eventually agreed to the war crimes trials despite the misgivings of some senior government officials who believed the decision to prosecute the surviving Nazi leadership for waging a war of aggression would set a dangerous precedent. They also feared the prosecutions would be on a par with the high-profile show trials in Stalin's Russia.

The insight into British thinking at the time that allied leaders were attempting to reach agreement over the political shape of postwar Germany is in a diary that Guy Liddell, head of counter-espionage at MI5, kept during the 1940s and 50s. Codenamed Wallflowers and supposedly kept in a safe in the office of successive MI5 director-generals, the wartime volumes of the diary have been declassified, and redacted copies of the postwar volumes are available at the National Archive.

Liddell supported a plan drawn up by the director of public prosecutions, Sir Theobald Mathew, for selected Nazis to be "bumped off" rather than put on trial, after a commission of inquiry had "come to the conclusion" this was the preferred option.

On 21 June 1945, Liddell dictated a diary entry to his secretary about a visit to his office by a British War Crimes Executive official, and representatives of MI6 and the Special Operations Executive, looking for evidence to support a war crimes prosecution.

"Personally I think the whole procedure is quite dreadful. The DPP had recommended that a fact-finding committee should come to the conclusion that certain people should be bumped off and that others should receive varying terms of imprisonment, that this should be put to the House of Commons and that the authority should be given to any military body finding these individuals in their area to arrest them and inflict whatever punishment had been decided on. This was a much clearer proposition and would not bring the law into disrepute.

"Winston had put this forward at Yalta but Roosevelt felt that the Americans would want a trial. Joe supported Roosevelt on the perfectly frank grounds that Russians liked public trials for propaganda purposes. It seems to me that we are just being dragged down to the level of the travesties of justice that have been taking place in the USSR for the past 20 yrs."

In July 1946, Liddell flew to Nuremberg with the deputy head of MI5, Oswald Harker, to watch the prosecution of 21 senior Nazis, including Hermann Göring ("considerably reduced in size") and Albert Speer ("probably one of the ablest in the dock").

There, he felt his fear that the tribunals would be little better than show trials had been confirmed. "One cannot escape the feeling that most of the things the 21 are accused of having done over a period of 14 years, the Russians have done over a period of 28 years. This adds considerably to the somewhat phoney atmosphere of the whole proceedings and leads me to the point which in a way worries me most, namely, that the court is one of the victors who have framed their own charter, their own procedure and their own rules of evidence in order to deal with the vanquished."

While the Nuremberg tribunals are now widely seen as a defining moment in international justice, providing the basis upon which war criminals could be brought to trial, Liddell thought it unwise to prosecute the Nazis for having waged a war of aggression. "One cannot help feeling ... a dangerous precedent is being created," he said.

The defendants

The Nuremberg tribunal opened in 1945. Two years earlier, the USSR, Britain, and the US had issued their Declaration on German Atrocities in Occupied Europe, which stated that when the Nazis were defeated, the allies would "pursue them to the uttermost ends of the earth … in order that justice may be done".

Twenty-four defendants were charged under four counts: crime against peace, planning and waging wars of aggression, war crimes, and crimes against humanity. They did not include Adolf Hitler, Heinrich Himmler, head of the SS, and Joseph Goebbels, head of propaganda, who had all killed themselves. Martin Bormann, the Nazi party secretary, was tried in absentia – his remains were found many years later in Berlin.

Robert Ley, head of the "Strength through Joy" movement, hanged himself before the trial started. Hermann Göring, Hitler's successor, killed himself with a phial of cyanide the night before he was to be executed.

Rudolf Hess, Hitler's former deputy, who flew to Britain in 1941 with what he called a peace plan, was given a life sentence. He killed himself in Spandau prison, Berlin, in 1987.

Albert Speer, Hitler's architect who was responsible for the mass exploitation of forced foreign labour, was jailed for 20 years. The man who supplied the slave labour, Fritz Sauckel, was sentenced to death, as were 12 others.

The Nuremberg tribunal gave its name to the "I was only obeying orders" defence. It also led to a series of international conventions on the laws of war, genocide, and human rights, and the setting up of the permanent international criminal court in The Hague. Richard Norton-Taylor

• This article was amended on Friday 26 October. The original version said the wartime volumes were declassified in 2005. They were in fact declassified this week. This has been corrected.