In a scandal that will inevitably embrace the Syrian and the British governments, a British prisoner in the hands of the Syrian state security police has been found dead in a Damascus prison only four days before he was to be handed over to British MP George Galloway to be taken home to Britain on the instructions of President Assad himself.

Dr Abbas Khan, who was arrested by Syrian government forces while working as an orthopaedic surgeon in the Aleppo region and held incommunicado for more than a year, “committed suicide” in the state interrogation centre at  Kfar Soussa in Damascus, according to Syrian security authorities.  Khan’s mother, Fatima, who was herself in Damascus and had seen her son four times in the past four months, was eagerly awaiting his release this weekend when she received a telephone call from a Syrian official to say that he had hanged himself with his pyjamas.

His family in London – where Abbas was born – had received a bundle of letters from him in the last few weeks expressing his delight at his imminent release.  “He was saying ‘I can’t wait to be back with you guys’,” his sister Sara told me today.  “He did not commit suicide.”  Dr Khan leaves a young wife and two children.  Even in Damascus, his death elicited expressions of shock and disbelief.  Unable to bring herself to identify her son’s body, his mother told her family she was leaving Damascus at once for Beirut.

George Galloway was flabbergasted.  When I telephoned him, he described Khan’s death as “inexplicable”.  He had just booked his air ticket to Damascus when he heard the news from Dr Khan’s family – and then from the Syrian deputy foreign minister himself.  “As yet, no satisfactory explanation has been given to me.  The idea of a man committing suicide four days before he was to be released is impossible to believe.  The Syrian government knows my stand on the war and on (American) intervention.  A Syrian minister called me on behalf of the president (Assad) to come to Damascus before Christmas and take Abbas Khan home.  We need an explanation.”

A spokesman for the Foreign Office said: "We are extremely concerned by reports that a British national has died in detention in Syria. "We are urgently seeking clarification of this from the Syrian authorities."

Quite apart from the grief and outrage of Khan’s own family, Syria is now certain to become embroiled in a political crisis that suggests President Assad may not be able to control his own security authorities.  Dr Khan was a London-born doctor and no longer had any political importance – he had been arrested after treating women and children in rebel-held areas of Aleppo well over a year ago – yet he was taken from the Azra prison where he was being held last week to the Kfar Soussa interrogation centre, a jail where inmates are held just after arrest and just before their release.

For a tragedy of this importance, for what many clearly believe to have been a murder – for a British citizen whose release has been ordered by President Assad himself only to be found dead in state security police custody – will require a full explanation not only from the Syrian government but from Assad himself.  Repeatedly, Assad has claimed that he is solely in charge of Syria, and – despite disquiet among Syrians at his decision to hand over his chemical weapons to the United Nations last summer – nothing has hitherto suggested that Assad’s word might be crossed.

Yet the death of Abbas Khan now raises the devastating possibility that there are those in authority in Damascus who want to challenge the power and prestige of their own president.  It is clear that the Syrians intended to make a conciliatory gesture towards the West by releasing Khan – yet his death suggests there are those who wish to destroy Assad’s chances of a reconciliation with Western powers which only a few months ago were set on destroying his regime in a military attack.

Faisal Mokdad, the Syrian foreign minister, has reported that guards visited Dr Khan at 7am to take him his breakfast but that when they returned to take him for exercise at 9am, he was hanging by his pyjamas.  The wife of another prisoner at Azra had told Khan’s family last week that he was taken from his cell by national security police who “wanted to ask him a few questions” before his release.  He left Azra alive.  The next that was heard was a statement from the Syrian authorities that he had “committed suicide”.

When originally arrested in 2012, Abbas Khan was believed to have been severely tortured – or so he managed to inform his family – but had later received better treatment.  Yet his very detention was difficult to explain.  He had apparently argued with rebel supporters in Aleppo about the medical equipment he had brought to Syria after crossing the border illegally from Turkey.  Some thought he should sell the provisions but Abbas Khan apparently insisted that they should be given away free.  

Abbas Khan’s brother Afroze was flying to Beirut on Tuesday to meet his mother at the Lebanese-Syrian border.  Last week, Afroze did say that he feared for his brother’s mental health – but the family explained on Monday that he was referring to Abbas’ feelings when held incommunicado, and that this no longer referred to his current mental state.  Afroze had been trying to put pressure on the Syrian authorities to bring forward the date of Abbas’ release – although the family realise that this original statement may now be used by others to ‘prove’ that Abbas may have taken his own life.

In private, the Indian-origin family complained at the unwillingness of the UK authorities to make any serious gestures on Abbas Khan’s behalf.  Mrs Fatima Khan had spent weeks in Damascus pleading for her son’s release, even hiring a lawyer to represent him in court.  Overwhelmed by a phone call to her hotel asking her to identify her son’s body, she refused to visit the hospital where his remains were held.