India's most wanted terrorist, Dawood Ibrahim - the man behind the 1993 Bombay serial blasts - has crippling gangrene in his legs, sources said Monday.

Doctors treating Dawood said his gangrene is in such an advanced stage, that soon they would have no option but to amputate his legs.

The crime boss, who is now immobile, is receiving treatment at his posh residence in the upscale Clifton neighbourhood of Karachi. He is currently being treated by doctors from the Liaquat National Hospital, Karachi, and the Combined Military Hospital, Karachi.

Sources told CNN-News18 that at such an advanced stage of gangrene, he is unlikely to be cured fully.

Doctors treating Dawood said the cause of gangrene is the loss of effective local blood supply due to his high blood pressure and blood sugar. Loss of blood supply deprives tissues of oxygen, causing cells to die.

Doctors also said the kind of gangrene that Dawood suffers from is life-threatening, and that a considerable amount of body tissue in his legs is already dead. The gangrene produces toxins which spread to the rest of the body.

Sources also said Dawood, who is under the protection of Pakistan's Inter-Services Intelligence (ISI), will not be moved out of the city of Karachi. A high-level meeting decided Army doctors will take the lead in his treatment and that support will be given to him in Karachi itself.

If Dawood’s condition worsens, and he dies in Pakistan, then it will be a big blow to India’s efforts to bring him to justice. There may not even be an official acknowledgement as Islamabad has always denied his presence in the country.

This could be a big let-down for families of victims of the 1993 blasts and the blame would fall on successive governments at the Centre. The best-case scenario for the Indian agencies was to lay a trap for him if he tried to move out of Pakistan.

Sixty-year-old Dawood is wanted in India for organising and financing the 1993 Bombay serial blasts which left 257 dead and 717 injured. The blasts were carried out with the help of his subordinates, Tiger Memon and Yakub Memon. In July 2015, Yakub Memon was hanged to death for this crime, while Dawood and Tiger are still free.