Prime Minister Ariel Sharon suffered a "significant" stroke with "massive bleeding" in his brain late Wednesday night, according to a Hadassah University Hospital official, and Sharon's authority has been transferred to Deputy Prime Minister Ehud Olmert.

In a brief statement outside the Jerusalem hospital, Dr. Shlomo Mor-Yosef said Sharon had suffered "a significant stroke," adding that he was "under anesthetic and receiving breathing assistance."

A few minutes later, Mor-Yosef emerged to say that initial tests showed Sharon had suffered a cerebral hemorrhage, or bleeding inside his brain. Addressing reporters in English, Mor-Yosef said Sharon had "massive bleeding and was being transferred to an operating theater."

Channel 2 TV said Sharon was suffering from paralysis in his lower body. Analysts on local TV stations said his life could be in danger.

According to one senior doctor who was basing his diagnosis on the information the Sharon?s doctors have released, the prime minister?s chances to return to full functioning were not high.

The doctor said that in many similar cases, a cerebral hemorrhage means the patient is under significant life threat.

Sharon was rushed to Hadassah Ein Karem shortly before 11 P.M. Wednesday night after feeling chest pains, less than three weeks after suffering a mild stroke and the day before he was to undergo a heart procedure.

He arrived by ambulance from his Sycamore Ranch in the Negev, a drive of more than an hour, and was taken into the emergency room at Hadassah Ein Karem, where he was scheduled to undergo a cardiac catheterization Thursday afternoon.

Sharon's authority was transferred to Olmert in the course of a telephone call with Olmert, Cabinet Secretary Yisrael Maimon and Attorney General Menachem Mazuz.

The Justice Ministry said Mazuz was being updated on Sharon's condition as the prime minister was being taken to the hospital and that Mazuz was to decide whether to transfer Sharon's powers after doctors examined him and consulted with Maimon.

However, once Sharon arrived at the hospital, it became clear that the severity of his condition necessitated general anesthesia, and Maimon and Mazuz decided they had no choice but to transfer Sharon's powers to Olmert.Sharon finished working at 3 P.M. Wednesday and went to his ranch. He was slated to begin fasting at midnight, ahead of the heart procedure.

A medical team gathered around Sharon, who was accompanied by his son Omri, as he came out of the ambulance, and witnesses said he was brought into the hospital on a stretcher.

Shortly after Sharon left for the hospital, Sharon aide Ra'anan Gissin told CNN that Sharon had felt some chest discomfort. "Apparently when he went back to his farm this evening he felt slight pains in the chest and some weakness, and in the presence of his doctor, and upon his advice, he said he should be taken to the hospital," Gissin said.

Shortly after the news of Sharon's condition broke, the White House said that the Americans' "thoughts and prayers" are with the prime minister and his family.

Hadassah Hospital spokesman Ron Kromer had earlier announced that the prime minister was in the trauma unit, and undergoing a series of examinations.

The hospital entrance was filled with police cars and security forces to prevent access to Sharon.

Maimon, military secretary Gadi Shamni and other members of Sharon's bureau arrived at the hospital shortly after the prime minister was admitted.

Sharon, 77, is extremely overweight, but doctors checking him after his December 18 stroke found him otherwise in good health. Doctors said he would not suffer long-term effects from the stroke, but they discovered a birth defect in his heart that apparently contributed to the stroke.

The catheterization procedure originally scheduled for Thursday afternoon was intended to close a small hole between the upper chambers of Sharon's heart. He was to have been put under general anesthesia during the operation, and his authority would have rested with Olmert for about three hours.