Ariel Sharon started breathing independently today and moved his right hand and foot as doctors began the process of waking him from the medically-induced coma he has been in since he suffered a massive stroke last week.

At the first reduction of anaesthetics this morning, the 77-year-old Israeli Prime Minister began breathing, said Dr Shlomo Mor-Yosef, the director of Jerusalem’s Hadassah hospital.

This afternoon, Dr Mor-Yosef told reporters that Mr Sharon had reacted to a series of stimuli, including pain, to test the extent of the damage caused by the stroke five days ago.

"We carried out pain stimulus tests which involve pressure. In the stimulus, we noted that the Prime Minister, Ariel Sharon, slightly moved his right arm and right leg," said Dr Mor-Yosef, who added that Mr Sharon's blood pressure also rose slightly during the tests, a positive sign.

"It was a very clear reaction to pain... These movements changed and became more and more significant the more we lowered the sedation," he said.

Dr Mor-Yosef described the results as "slight but significant" but insisted a clear assessment of any brain damage caused by the stroke and the three brain operations that followed it would have to wait for the coming days, as Mr Sharon is gradually returned to consciousness.

Dr Felix Umansky, the chief neurosurgeon treating Mr Sharon, said that the patient's eyes were still closed and that he would only be satisfied that he would recover when Mr Sharon is "sitting up in bed and talking".

"It is still too early to speak about cognitive function," said Dr Umansky. "It will take a number of days."

When Mr Sharon's condition is known, his doctors will tell Israel's Attorney General, Meni Mazuz, whether they believe he will able to resume his duties as Prime Minister.

If doctors rule that Mr Sharon is permanently incapacitated then an emergency meeting of the Cabinet will be called to appoint a new Prime Minister, who will be able to serve for 100 days before an election must be held.

Today's positive news comes after a brain scan yesterday which led doctors to express slight optimism about Mr Sharon's condition, though they said he was still critical but stable.

With hopes growing that Mr Sharon could survive, Ehud Olmert, the acting Prime Minister, projected a business-as-usual image when he conducted the first weekly Cabinet since the former general was stricken on Wednesday night.

The mood was sombre in the Cabinet room and Mr Sharon’s chair was left symbolically empty. But the ministers were buoyed by the signals that Mr Sharon might pull through.

Mr Sharon’s collapse has thrown Israeli politics into turmoil because he had quit his ruling Likud party and formed Kadima to fight the general election, just 11 weeks away.

However, Shimon Peres, 82, the former Prime Minister who quit Labour to endorse Kadima, threw his weight unequivocally behind Mr Olmert and scotched rumours that he might return to his old party.

"I’m not negotiating with Labour," he said. "I came to join Ariel Sharon with the sole and main purpose of advancing the peace process, and that will guide my activities." Mr Peres said that though Kadima without Mr Sharon’s leadership was diminished, it remained a viable party for the centre.

Mr Peres was asked if Mr Sharon had outlined the vision of Kadima to him. "I think I have a fair idea," he said. "I don’t know precisely, but I know in general terms where Mr Sharon was aiming. First of all, we are out of Gaza; we shall not return there.

"Secondly, it won’t be Gaza first and Gaza last. There will be a continuation after Gaza in the West Bank."

Times Recommends

• It’s only Brits who don’t appreciate me, says Blair
• Party’s over for Greek graspers
• White House tightens security for Xmas marathon