Israeli Prime Minister Ariel Sharon remained in critical but stable condition after undergoing a third surgery within two days to stem bleeding in his brain, a hospital official said Friday.

The CT scan showed, however, that the 77-year-old leader had "significant improvement" and was returned to an intensive care unit after the five-hour operation, Director of Jerusalem Hadassah Hospital Dr. Shlomo Mor-Yosef told reporters outside the hospital.

He said that there is no active bleeding in Sharon's brain and intracranial pressure has returned to normal.

"After the operation, we transferred the prime minister to the CT scan unit to determine the state of his brain," Mor-Yosef said. "I can say that in comparison to his previous CT scans, there has been a significant improvement in the way the brain looks to Hadassah neurology experts."

Doctors were impelled to perform the third surgery after a brain scan Friday morning revealed an increase in cranial pressure and new bleeding, said Mor-Yosef.

Before the surgery, doctors said they were planning to keep Sharon sedated and on a respirator at least until Sunday to give him a chance to recover.

However, Sharon's doctors acknowledged Thursday night that Sharon has probably suffered irreversible brain damage that would preclude his ever resuming office.

Meanwhile, acting Prime Minister Ehud Olmert met with Shimon Peres on Friday, discussing continuing policies of Ariel Sharon.

The policies include "an unhesitating war on terror, as well as an unending effort in the direction of the peace process," Peres said.

Olmert met with Peres to keep him staying in Kadima, a new party that Sharon created after he quit the Likud last November. Olmert's move came as an effort to block any attempt by Labor Party Chairman Amir Peretz to return Peres to the Labor.

Peretz said that the Labor has offered to assist Olmert in an effort to ensure proper management of the state's affairs.

"Israel's military and social government structures are complex and extensive, thus as Labor Party chairman I promise to give the acting prime minister any needed assistance in order to stabilize these structures," he said.

Peretz said his party has suspended all its primaries and election activity due to Sharon's health problems.

A survey showed on Friday that Sharon's party, Kadima, would win 40 Knesset (parliament) seats among 120 if elections were held as of Thursday and the party were to be headed by Olmert.

The survey also showed that were Shimon Peres to take over leadership of the party, Kadima would win 42 seats -- exactly the number of seats it would have garnered four days ago, when Sharon was still healthy.

The Ha'aretz daily said the impact of the survey is limited, as it was conducted in the eye of the storm, at the height of uncertainty, polling a public awash in sympathy for Sharon, who is fighting for his life.