Ariel Sharon is failing to wake from a medically induced coma, according to unconfirmed reports in Israeli media.

Surgeons have gradually reduced the level of anaesthetic used to keep the Israeli Prime Minister under sedation since he suffered a severe stroke and brain haemorrhage nine days ago.

But the reduction in anaesthetic has been accompanied by only a slight improvement in responsiveness, and the Israeli leader has not regained consciousness or opened his eyes, according to medical sources quoted on Israeli public radio.

"The situation is worrying, very worrying," the source is quoted as saying. "The moment of truth is approaching."

"If there is no sign of improvement, it would need a miracle for Sharon to wake up from his deep coma and be able to function in a way close to normal," the source said.

Officials at the Hadassah Hospital in Jerusalem where Mr Sharon is being treated played down the renewed concerns. Until today, official reports have been remarkably upbeat, reinforcing the 77-year-old's reputation for near-infallible resilience.

Today, a hospital spokesman said that he remained in a "serious but stable" condition. Ron Krumer told AFP: "We have been worried from the start, we continue to be and we are saying that his condition is serious."

Mr Krumer confirmed that Mr Sharon had been in a coma for nine days, but stressed the length of time such patients remained unconscious varied. "This is something that differs from one patient to another," he said. "We have expressed our concern since the beginning and we have not changed."

A brain scan yesterday showed that remnants of blood in Mr Sharon's brain have been absorbed, the hospital said. In response, doctors removed a tube they had inserted into his skull to relieve pressure on his brain.

According to one expert, the more time that passes without Mr Sharon reawakening the lower his chances of a full recovery.

"If there was no brain damage, I would have expected him to wake up at this point," said Dr. John Martin, a professor of cardiovascular medicine at University College in London.

Mr Sharon has been through three bouts of surgery to stem bleeding in his brain since being admitted to intensive care on January 4, leaving Israelis increasingly resigned to the likelihood that he will never return to government.

Ehud Olmert, the acting Prime Minister, looks likely to remain in charge until the general election in March.

An opinion poll published in the mass selling Yediot Aharanot newspaper revealed that an overwhelming 87 per cent of those interviewed doubted that Mr Sharon would ever return to his duties as prime minister.

Nevertheless, the Kadima party that the Israeli Prime Minister founded just six weeks before his collapse has maintained a lead over rivals in the latest opinion polls.

The polls, conducted by the Maariv and Yediot Aharanot newspapers, gave Kadima 43 and 42 seats respectively in the 120-member parliament. The centre-left Labour party would win 17 and Sharon’s crisis-ridden former Likud party, which has lurched towards the right, 16 seats according to Maariv or 13 as reported by Yediot.

Mr Olmert, who is now almost certain to lead Kadima to the March 28 election, was also favourite to be elected premier with 45.7 per cent, well ahead of Likud leader Binyamin Netanyahu with 26.6 per cent.

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