The official inquiry into Nazi atrocities committed on Alderney in the Channel Islands is under pressure to investigate why those responsible for committing war crimes on British soil were never brought to trial in the UK.

Prof Anthony Glees, the security and intelligence expert who advised Margaret Thatcher’s war crimes inquiry, told the Observer: “This is a vital opportunity to establish all the facts, and it must examine why those who perpetrated such heinous war crimes were never brought to trial in this country. The review into the atrocities on Alderney is to be warmly welcomed, but I believe it should not just focus on the numbers killed, as important as that is.”

Last week the Observer revealed that the UK’s Holocaust envoy, Lord Pickles, would be launching an inquiry into the number of prisoners murdered by the Nazis in the British crown dependency. But Glees said the investigation needed to delve more widely into the events on the Channel Island to uncover the truth about one of the darkest episodes of British history. He added that the events on Alderney had been excluded from his inquiry in 1989.

Glees said that after the second world war the guiding principle was that war criminals were handed over to the country where their crimes were alleged to have been committed. “Those who were responsible for the crimes on Alderney should have been put in the dock at the Old Bailey,” he said. He said he would be writing to Pickles to urge him to extend the remit of the inquiry.

Glees’s call was backed by Labour MP Dame Margaret Hodge, who is the daughter of Jewish refugees who fled the Nazis. “The inquiry must investigate why the Nazi officers responsible for such barbarities on the Channel Islands were released by the British authorities and never brought to justice,” she said.

Hundreds of prisoners are known to have been killed when the Nazis occupied Alderney and set up slave labour camps, including at least one that was taken over by the SS to be used as a concentration camp. The senior Nazi officers in charge of Alderney were arrested by the British authorities after the island was liberated but were never tried for their actions.

Glees believes the number of people murdered on Alderney or sent from the island to extermination camps in Europe will run into the thousands.

An investigation published by the Observer more than 40 years ago revealed that the British government’s official story that the Kommandant of Alderney, Major Carl Hoffman, had been handed over to the Soviet authorities was untrue. It emerged that Hoffman, after being held in the UK until 1948, was released to West Germany, where he died peacefully in 1974.

After the war, Britain sent a military intelligence officer, Capt Theodore Pantcheff, to investigate Nazi atrocities on Alderney. He reported that Hoffman had been hanged in Kyiv. Approached by journalist Solomon Steckoll in the 1980s with evidence that this was not the case, Pantcheff said: “It is inconceivable that information which was officially put out, if this was not true, could have been other than the result of a policy decision at Cabinet level.”

Nor was Hoffman an isolated case. Hauptsturmführer (Captain) Maximilian List was in charge of the SS Camp Sylt on Alderney. After the war he was traced to a British prisoner of war camp and was said to have been handed over to the Russian authorities. In fact he was living in West Germany well into the 1970s.

Obersturmführer Kurt Klebeck, List’s deputy, lived out his days in Hamburg despite German investigations in the 1960s and the 1990s. In 1992, the Guardian journalist Madeleine Bunting tracked Klebeck down to Hamburg. The Jewish Labour MP David Winnick led the parliamentary campaign for him to be brought to justice but he was never extradited.

Pickles launched the review of evidence into the number of prisoners who died on Alderney during the Nazi occupation on 20 July. An international panel of experts will receive assistance from Yad Vashem, the World Holocaust Remembrance Center in Israel.

Pickles tweeted on Saturday: “I look forward to reading Prof Glees’s letter and his evidence. The review will not be able to solve everything, but settling the numbers will be a good start. It’s shameful that Hoffman & List did not face justice. Shockingly, all too common after WW2.”

Dr Kathrin Meyer, secretary general of the International Holocaust Remembrance Alliance , said: “The IHRA hopes the review is the beginning and not the end of a more detailed understanding of this important chapter in our history.”

The tiny Channel Island was home to a number of Nazi slave labour camps where thousands were brought to help build the German defences known as the Atlantic Wall. It has now been established that the SS took over at least one camp and ran it under the principle of Vernichtung durch Arbeit – extermination through labour.

Other inmates were tortured, shot or given fatal injections, and those sick or unable to work were sent to extermination camps in occupied Europe.

The official number of deaths is in the hundreds, though some claim it could be in the thousands, with many buried in mass graves. Only eight Jews are reported to have died, but the true number is thought to be much higher.