Ariel Sharon, Israel’s 77-year-old prime minister, will undergo further tests today and remain in hospital for several days after suffering a minor stroke last night.

Mr Sharon was rushed to Hadassah Hospital in Jerusalem after feeling faint, confusing words and briefly losing consciousness, according to reports.

Doctors said he underwent tests, including a brain scan, and responded quickly to treatment, showing no lasting effects.

Boleslav Goldman, Mr Sharon’s personal physician, said he would "be in hospital for a few days for sure" after being given medicine to thin his blood. "There is no reason for fear," he said.

Aides said that Mr Sharon, who is considerably overweight, had told them, "I feel fine" and that he had quipped to doctors: "You’re still not getting rid of me."

This morning, Mr Sharon was alert and held his daily staff meeting in the hospital, according to an aide. "He asked questions, he received an update from the military secretary and from the Cabinet secretary. He’s in good spirits," Asaf Shariv told Army Radio.

Haaretz, a daily newspaper, reported that one of its reporters spoke to Mr Sharon late night. "I’m fine," he is reported to have said.

"Apparently I should have taken a few days off for vacation. But we’re continuing to move forward," said Mr Sharon, punning on the name of his new party, Kadima, which means "forward."

Despite Mr Sharon's quick recovery, question marks over his health come at a crucial juncture in Israeli politics, just weeks after he dramatically quit his Likud group to form the new party and call a general election.

With the poll only 14 weeks away, Kadima has been riding high in the opinion polls, leaving both Likud and the opposition Labour party in its wake.

But as the architect of the summer’s Gaza withdrawal from Jewish settlements, Mr Sharon is Kadima’s key electoral asset and question marks over his health could yet affect the March 28 election.

The Yediot Aharonot newspaper ran a front page editorial today under the headline: "The Main Thing is Health".

"Kadima’s existence depends on one man: Ariel Sharon. He is almost 78 years old, and as became apparent yesterday, he is not Superman," said the newspaper. "Sharon will have to answer questions regarding the question of succession: What will happen in his cabinet in such a case; what will happen in his party."

Before suffering the stroke yesterday, Mr Sharon had had a meeting at his Jerusalem office with Shimon Peres, the former Labour leader who has also thrown his weight behind Kadima. Mr Peres said that the Prime Minister had appeared fine and been in good spirits.

But shortly afterwards, he was on the phone to his younger son, Gilad, as he travelled to a another meeting by car and complained of feeling unwell. Aides diverted his convoy towards the hospital but he lost consciousness for a short time during the journey, according to a doctor. Mr Sharon’s office later denied that he was unconscious at any time.

Last year, Mr Sharon underwent minor surgery for the removal of a cancerous growth on his face and three years ago he had an operation to remove kidney or gall stones.

However, if he were incapacitated for any length of time, his long-time ally and deputy prime minister Ehud Olmert, who also defected to the Kadima party, would act as caretaker premier.

Mr Sharon received several goodwill messages from world leaders. Mahmoud Abbas, the Palestinian President, wished Mr Sharon a speedy recovery, as did the White House. But in the Gaza Strip, some Palestinians fired rifles in the air, shouting, "Death to Sharon".

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