The body of a British surgeon who died in a Syrian jail where he alleged he had been tortured has been flown back to the UK, where a post-mortem will be conducted.

The body of Abbas Khan, 32, was found in his cell last week, only days before he was due to be released.

Khan's family and the Foreign Office allege that he was murdered, but Syrian authorities claim that he committed suicide, hanging himself with his pyjamas.

A Red Cross vehicle took Khan's body to Lebanon, where his mother, Fatima, and brother, Afroze, were waiting to accompany it back to London.

The coffin arrived at Heathrow, from where it was taken to an east London coroner's office for post-mortem examination.

Michael Mansfield QC, who has said he will represent the family if necessary, said the death seemed to be a "clear case of murder".

Last week, the Foreign Office called his death "very suspicious".

A Metropolitan Police spokesman said that the force's Counter Terrorism Command was providing family liaison, and would assist the coroner as appropriate.

Khan arrived in Syria in November 2012, after crossing the border from Turkey. He worked at a field hospital in rebel–controlled Saraqeb, south–east of Idlib, where his family say he treated civilian casualties.

He was arrested in Aleppo only 48 hours after arriving in the country, and in letters to his family said that he was abused in custody.

"My detention has included repeated and severe beatings, largely for no reason other than the pleasure of my captors. In addition I have been violently forced to beat other prisoners, kept in squalid conditions, denied access to toilets or medical treatment," he wrote in one letter.

Respect MP George Galloway had been in Syria working to secure Khan's release, and was assured by officials that the orthopaedic surgeon would be freed before Christmas, on the order of the country's president, Bashar al-Assad.