London: Terming the death of an Indian-origin British doctor in a Syrian jail as "sickening", British Prime Minister David Cameron has said Damascus must "answer for" the "appalling tragedy" and bring to justice those responsible for it.
In a condolence letter to 32-year-old Abbas Khan`s mother Fatima, Cameron wrote on Friday, "Abbas` death is a sickening and appalling tragedy and it is right that the Syrian regime should answer for it.
"Their despicable treatment of him and refusal to engage with us or the Czechs to enable us to support him is utterly unacceptable. We will continue to press for those responsible to be held to account."
The news of the letter emerged as the body of the orthopaedic surgeon returned to the UK, where another post-mortem examination is to be conducted.
The father of two from south London was found dead in his cell just days before the Syrian government had said he would be freed.
Khan`s family insist he was murdered while the Syrian authorities claim he took his own life.
He had been arrested in Syria 48 hours after arriving in the country for humanitarian work last November.
"We want the British government to help the family in getting those answers from the Syrians as somebody needs to own up for this absolutely cruel injustice that has been done to my brother," Khan`s sister Sara said.
A Metropolitan Police spokesperson said its Counter Terrorism Command was providing family liaison support and would "seek to assist the coroner when appropriate".
Khan went to Syria last year to work in a field hospital in a rebel-controlled area.
The doctor who worked at the Royal National Orthopaedic Hospital (RNOH) in north-west London had entered Syria without a visa after bring moved by the plight of refugees and worked in camps in Turkey, his family said.
The UK Foreign Office said the doctor had been "in effect murdered" by the Syrian authorities and at best his death was "extremely suspicious".
The Syrian government claims Khan hanged himself in his cell in Damascus last Monday, using his pyjamas as a noose ? four days before he was due to be released.