Israeli Prime Minister Ariel Sharon will remain under deep sedation and on a respirator for at least 48 hours, the director of Jerusalem Hadassah Hospital said Thursday evening.

"This is a lengthy process," Dr. Shlomo Mor-Yosef said, adding that it will take at least 48 hours for Sharon to regain consciousness after a surgery.

He said sedation and respirator as part of the treatment would decrease pressure in the prime minister's skull.

After the sedation period, doctors hope to waken Sharon gradually, Mor-Yosef said, adding "Sharon's pupils are responding to light, which means the brain is functioning."

"We are fighting for the life of the prime minister, with no compromise," he said.

The hospital chief also defended the decision on taking Sharon to the Jerusalem hospital, a journey of an extra 30 minutes, rather than to the nearer medical center in the Israeli city of Be'er Sheva, saying it was better for the prime minister to be treated at the hospital that knew his case.

Mor-Yosef said that the operation on Sharon had focused on the right side of his brain and he was paralyzed during the procedure.

"The paralysis was a paralysis that we, the doctors, created," he explained.

Neurosurgeons fought to stabilize Sharon's condition and stop new bleeding detected in his brain Thursday morning, nine hours after Sharon was rushed to emergency surgery following a "far-reaching" stroke and a massive brain hemorrhage late Wednesday.

A neurosurgeon said on Thursday that Sharon's chances of staying alive have been very slim since the beginning of the cerebral hemorrhage.

A short while after 1:00 a.m. (2300 GMT Wednesday), Sharon's personal physician Dr. Shlomo Segev told reporters, "The prime minister is in surgery, the surgery is going as planned. We need to be patient. I have nothing else to add."

Prime Minister's spokesman Raanan Gissin said that "once the operation ends, the public will be notified. Until then, I suggest not to engage in speculation."

According to a medical expert, the procedure is life threatening. Asked what are the chances of surviving this type of surgery, the doctor replied, "Let's be optimistic, some people survive it."

The prime minister's close associates said of his condition Wednesday night: "hope for a miracle."

Justice Ministry spokesman Ya'acov Galant said that a prime minister legally remains in his post only if he is capable of making decisions.

Since Sharon is not conscious after suffering from what doctors called "a serious stroke," his powers and prerogatives were transferred to his deputy and Finance Minister Ehud Olmert.

Olmert convened a special cabinet meeting on Thursday morning at 9:00 a.m. (0700 GMT) to brief the ministers on the temporary transfer of powers.

It initially appeared that Sharon's condition was not severe. According to well-placed sources, there were two deteriorations, the first just prior to his arrival at Hadassah Hospital and the second, upon entering the trauma unit.

While on his way to the hospital, Sharon's spokesmen claimed that the prime minister was conscious and able to speak, but had complained that he was suffering from weakness and "felt ill."

The prime minister initially complained of feeling chest pressure and pain. Two Sharon associates said the prime minister was feeling unwell at his Negev ranch, and following a discussion with his personal doctor, decided to be taken to the hospital.

After suffering a mild stroke 18 days ago, the prime minister had been scheduled to undergo a heart procedure Thursday morning.

However, the procedure was reportedly delayed due to the Wednesday evening event.

Sharon was seeking re-election in the March 28 election as head of a new centrist party, Kadima. He was enjoying a lead in polls. The party's strength is centered on Sharon himself, and if he were forced to leave the scene, Israel's political scene would be thrown into turmoil.