With his chair empty and a small brown gavel lying untouched in front of it, ailing Prime Minister Ariel Sharon was declared permanently incapacitated by Israel's Cabinet on Tuesday, officially ending his five-year tenure.

Sharon, 78, suffered a devastating stroke Jan. 4 and has been in a coma since.

After the stroke, Sharon's deputy, Ehud Olmert, immediately stepped in as his temporary replacement. Olmert has since won national elections as leader of the centrist Kadima Party, and has become the designated prime minister, assigned the task of forming a coalition government.

Tuesday's declaration was largely symbolic in nature since Olmert has been Israel's de facto leader since January, and because medical experts believe Sharon's chances of recovery are slim.

Under Israeli law, an ailing prime minister can only have a temporary replacement for up to 100 days before an official successor must be named. That deadline expires Friday, but because the weeklong Jewish Passover holiday begins Wednesday, the declaration of permanent incapacitation was moved up to Tuesday.

"Today, we realize that he is not with us anymore in the political arena, that he could not see the results of what he initiated, the Kadima Party," said Cabinet minister Meir Sheetrit of Kadima.

Cabinet Secretary Israel Maimon noted at the beginning of a special Cabinet session that Friday marks the end of the 100-day period.

"According to the law, at the end of 100 days, the government must appoint a minister from his party as the acting prime minister, until the establishment of a new government. The suggestion laid forth today is to appoint the head of the Kadima party, the acting prime minister Ehud Olmert, as the prime minister in practice."

Sharon has been lying unconscious since his stroke. Last week, surgeons reattached a portion of his skull removed in previous surgery. It was his eighth operation since he fell ill.

Sharon underwent a CT scan on Monday to determine the outcome of surgery on his skull last week, Hadassah Hospital spokesman Ron Krumer said. The scan revealed no change in his condition, which the hospital defines as "serious but stable," meaning that his life is not in immediate danger.

Hadassah officials have said that discussions were still under way on whether to move Sharon to a long-term care facility. Experts say his chances of recovery are extremely slim, given the gravity of his stroke and his persistent coma.

Sharon suffered the stroke weeks after leaving the hawkish Likud Party and forming the new centrist Kadima movement, pledging to pull out of large parts of the West Bank and draw Israel's final borders by 2010.

Sharon had been expected to coast to a third straight term as prime minister, and his removal from the political scene shocked Israelis.

Led by Olmert, Sharon's heir apparent, Kadima won last month's Israeli election, although by a smaller margin that was expected when Sharon led the party. Analysts have said the party's popularity was a result of Sharon's legacy.