The accused Nazi war criminal John Demjanjuk has begun his trial in Munich.

The 89-year-old Ukrainian, charged of being an accessory to the murder of 27,900 Jews at the Sobibor camp, arrived at court in a wheelchair, accompanied by two guards and two doctors.

The start of the trial was delayed for 70 minutes after hundreds of people descended upon the Munich courtroom, attempting to gain entry to witness the trial.

Mr Demjanjuk says he was a prisoner of war captured by the Nazis from the Red Army. But prosecutors allege the Ukrainian had willingly become an SS guard at the Sobibor death camp where 250,000 people, mostly Jewish victims, were killed.

He could face up to 15 years in prison, and is unlikely to survive such a lengthy sentence, due to a serious bone marrow disease.

Because of Mr Demjanjuk’s ill health, court sessions will be held in just two 90 minute intervals per day.

Mr Demjanjuk emigrated to the US in the early 1950s, where he lived in Ohio and worked as a car mechanic.

In 1981, a court in Ohio found him guilty of lying on his immigration form, hiding his SS membership. He was deported to Israel where he was identified by survivors in Israel as "Ivan the Terrible," a Ukrainian staff member at Treblinka.

Demjanjuk was found guilty of crimes against humanity at both Sobibor and Treblinka. He was sentenced to death in Israel in 1987.

He spent seven years in prison but after launching an appeal, claiming mistaken identity, he was acquitted in 1993.

But more paperwork was uncovered about Demjanjuk’s time at Sobibor and he was deported to Germany earlier this year.

Even if Demjanjuk is acquitted, he is unlikely to be able to return to the US and will probably have to remain in Germany.

Witnesses at the trial this week will include former camp guard Ignat Danilchenko, who will allege that Mr Demjanjuk would go on “Jew hunts” around the countryside to bring people to the death camp.

But defence lawyers insist that there are inconsistencies in Mr Danilchenko’s account.

Lord Greville Janner, Chairman of the Holocaust Educational Trust, commented on the opening of the trial: “There can be no time limit on securing justice for the victims of the Holocaust. It is essential that we keep working to ensure that the perpetrators of heinous crimes are brought to trial and that we continue to raise awareness and educate future generations about the Holocaust.”