Grieving relatives of a British surgeon who died in a Syrian prison after more than a year behind bars say they still have unanswered questions.

Dr Abbas Khan, an orthopaedic surgeon from south London, went to Syria to provide medical aid to both sides in the civil war.

He was apprehended within 24 hours of arriving in the country and spent 13 months in prison in Damascus, where he said he suffered repeated beatings and squalid conditions.

His brother, Shahnawaz Khan, told ITV News that his mother had travelled to Syria in anticipation of his imminent release when news of his death came.

Foreign Office minister Hugh Robertson has accused the Syrian Government of "in effect" murdering Dr Khan.

ITV News correspondent Juliet Bremner reports:

According to the BBC, Syria's deputy foreign minister Faisal Mekdad announced that Mr Khan had committed suicide in prison.

But Shahnawaz Khan told ITV News that he did not believe such rumours:

He was happy, he knew he was being released. I have a letter saying that he feels he has been granted an amnesty, and we thought we would celebrate Christmas with him next week. To say that we feel our hearts have been ripped out is an understatement.

He also said he felt "abandoned" by British officials who he accuses of treating his brother "like he's been caught drinking on the streets of Dubai" instead of as a humanitarian worker.

Watch: Family of British surgeon feels 'abandoned' by officials

George Galloway, who has been negotiating with Syrian authorities to secure Dr Khan's release, called news of his death "heartbreaking and devastating".

The MP for Bradford West revealed that he was due to fly to Damascus on Friday to bring him back to Britain.

The Foreign Office (FCO) insists it will be pressing the Syrian regime for answers over Dr Khan's death in prison.

"If these tragic reports are true responsibility for Dr Khan’s death lies with them and we will be pressing for answers about what happened," an FCO statement read.

It added: “We have consistently sought consular access to Dr Khan and information on his detention, directly and through the Russians, Czechs and others."

Read: Britain's 'impotent rage' over surgeon's death in Syria