The body of a British doctor who died earlier this week in a Syrian prison, only days before he was expected to be freed after 13 months of detention, has arrived in Beirut en route to the United Kingdom.

A Red Cross ambulance carried the coffin of Abbas Khan, a 32-year-old orthopaedic surgeon from south London, across the Syrian border into Lebanon on Saturday, where it was met by family members and British embassy staff.

Khan, a volunteer with London-based charity Human Aid UK and father of two, had travelled to Aleppo, in northern Syria, in November 2012 when he was arrested by the Syrian government.

Khan's family had been told he would be released earlier this week, but when his mother, Fatima, went to visit him in prison in Damascus on Monday, she was told he had died.

She accused Syrian President Bashar al-Assad's intelligence services of killing her son.

"They murdered my baby, they killed my baby, this is murder," she told reporters in Beirut on Saturday.

Torture claims

Syrian authorities said on Wednesday that Khan had committed suicide in his prison cell.

"He took off his pyjamas, hooked it to something in the window... and committed suicide," Faisal Mekdad, Syria's deputy foreign minister, told the BBC.

The British government has held Damascus responsible for Khan's death.

"Syrian authorities have in effect murdered a British national who was in their country to help people," said Hugh Robertson, a minister at the UK Foreign Office.

In letters to British Foreign Secretary William Hague before he died, Khan said he had been tortured in detention and kept in isolated, squalid conditions.

More than 1,000 people are thought to have died in the custody of Syrian state security, according to London-based human rights group Amnesty International.

Over 100,000 people have died in the war in Syria since it began in 2011.

Source: Agencies