Asma al-Assad is gravely ill with leukaemia and has been given a “50/50” chance of survival, according to reports.

She is currently in Moscow, where her father, Fawaz Akhras, is helping to care for her.

In May, Syria’s presidency announced that the then-first lady had been diagnosed with acute myeloid leukaemia – an aggressive cancer of the bone marrow and the blood.

Her cancer is believed to have reappeared after a period of remission.

A source close to the family told the Telegraph: “When leukaemia comes back, it’s vicious.

“She has been 50/50 in the last few weeks.”

The 49-year-old is believed to have flown to Moscow for treatment shortly before her husband’s regime was toppled by Syrian rebels.

Her father, a respected cardiologist, has been looking after her for much of the past six months.

Mrs Assad grew up in Acton, west London with her father, mother and two brothers and holds British citizenship.

She gained a first in computer science from King’s College London and went into investment banking, before dating Assad in 1992.

In recent days, reports emerged claiming she wanted to divorce her husband, an allegation dismissed by the Kremlin, and return to the UK for medical treatment.

However, that option appears increasingly unlikely, given political opposition to the move.

The government has indicated it would be unwilling to tolerate her presence in the UK.

The Foreign Secretary David Lammy said this month: “I want it confirmed that she’s a sanctioned individual and is not welcome here in the UK.”

He added he would do “everything I can in my power” to ensure no member of the Assad family “finds a place in the UK”.