The man convicted of the Lockerbie bombing has been found apparently comatose in a palatial villa in north Tripoli.

Abdelbaset al-Megrahi is slipping in and out of a coma and only being kept alive with oxygen and an intravenous drip, according to relatives attending him at the property, which they said had been ransacked by looters who plundered all his medicine.

Megrahi, last seen at a televised rally in Tripoli last month alongside Muammar Gaddafi, was tracked down by CNN international correspondent Nic Robertson."He appears to be a shell of the man that he was, far sicker than he appeared before … at death's door," Robertson said.

Megrahi's son, Khaled, told the broadcaster: "There is no doctor, there is nobody to ask and we don't have a phone line to call anybody."

Megrahi was discovered as the Libyan rebels' National Transitional Council (NTC) ruled out extraditing him to Britain. The justice minister, Mohammed al-Alagi, said: "We will not give any Libyan citizen to the west. Megrahi has already been judged once and he will not be judged again. We do not hand over Libyan citizens. Gaddafi does."

Megrahi is the only man convicted over the December 1988 bombing of Pan Am flight 103, which killed 270 people, mostly Americans, when it exploded over the Scottish town of Lockerbie. He was freed on 20 August 2009, after prison doctors said he had prostate cancer and probably had only three months to live. East Renfrewshire council, which received regular updates on Megrahi's condition from the Gaddafi regime, had been trying to locate him after the rebels' captured the Libyan capital.

The Scottish government and East Renfrewshire council issued a joint statement saying there had been contact through Megrahi's family over the weekend.

They said: "There was no evidence of a breach of his licence conditions, and his medical condition is consistent with someone suffering from terminal prostate cancer. Speculation about Megrahi in recent days has been unhelpful, unnecessary and indeed ill-informed."

"As has always been said, Al Megrahi is dying of a terminal disease, and matters regarding his medical condition should really be left there.

"It is in no-one's interest for there to be a running commentary on either Mr Al-Megrahi's medical condition or location, and we have no intention of providing one.

"Any change in Al-Megrahi's circumstances would be a matter for discussion with the National Transitional Council as the legitimate governing authority in Libya."

The NTC's comments on extradition are also an apparent blow to British hopes of putting on trial the suspected killer of Yvonne Fletcher, the police officer shot dead in 1984 outside the Libyan embassy. Scotland Yard has identified a former Libyan diplomat as the prime suspect.

The foreign secretary, William Hague, welcomed a pledge by the NTC chairman, Mustafa Abdel Jalil, to "co-operate fully" with extradition. But the justice minister's comments appear to cast doubt on the possibility.

No one has been prosecuted over the murder of WC Fletcher. But it has emerged that a witness saw Abdulmagid Salah Ameri, then a junior diplomat, firing a gun from inside the building. Libya has an extradition agreement with the UK, but it covers foreign suspects rather than Libyan nationals.