LONDON, England (AFP) — British Prime Minister David Cameron has written to the mother of a British doctor who died in a Syrian jail, saying Damascus must answer for his “sickening” death, the family’s lawyer revealed yesterday.

Syria claims Abbas Khan, who was arrested last year after travelling to Aleppo to treat wounded civilians, committed suicide. But a British minister said last week that he was “in effect murdered” by the regime.

Cameron accused the regime of subjecting Khan, a father of two, to “despicable treatment”, but the doctor’s family, who have criticised Britain’s efforts to secure his release, called the letter “too little too late”.

“Abbas’s death is a sickening and appalling tragedy and it is right that the Syrian regime should answer for it,” said Cameron’s letter, according to a copy sent to AFP by Nabeel Sheikh, the family’s lawyer.

“Their despicable treatment of him and refusal to engage with us… to enable us to support him is utterly unacceptable,” he added.

The prime minister, whose first son died in 2009, said he understood that words could do little to ease Fatima Khan’s pain in losing a child and paid tribute to her “courage and fortitude” during the 13 months of his detention.

“I cannot begin to imagine how devastating losing Abbas must be, especially at a time when it seemed as if the regime might finally release him,” he continued.

“I hope that you can draw some comfort from the outpouring of support you have received, and that you have space and time to grieve for him, as well as celebrate, with pride, the fact that he dedicated so much of his life helping others, including some of the most vulnerable in the world.”

The prime minister vowed to “press for those responsible to be held to account”.

But Sara Khan, the dead man’s sister, doubted he would be successful.

“Is he going to actually now manage to get some answers from the Syrians?” she asked, during a Sky News interview.

“Are they going to be able to answer why my brother was killed, how he was killed, by who he was killed?

“A sympathising letter is not enough to justify someone’s death. It is just too little too late.”