JERUSALEM Ñ Prime Minister Ariel Sharon's has been forced to call off plans for an imminent summit with U.S. President George Bush to win his endorsement of an Israeli unilateral withdrawal plan from the Gaza Strip and parts of the West Bank.

Sharon had sought to obtain a meeting with Bush in late February. But the White House refused to schedule a date amid concern that an Israeli unilateral withdrawal plan could destabilize the region and harm the U.S. military effort in Iraq.

[On Tuesday, Israeli military intelligence chief Maj. Gen. Aharon Zeevi Farkash told the Knesset Foreign Affairs and Defense Committee that Palestinian insurgency groups would regard the unilateral Israeli withdrawal from the Gaza Strip as a victory. Farkash said these groups, which are expected to increase attacks from the West Bank, as well as the Palestinian Authority are already preparing for the prospect of such an Israeli withdrawal.]

Aides to Sharon said an operation that took place on late Monday could sideline the prime minister for at least several weeks, Middle East Newsline reported. They said Sharon, under advice of his physicians, will probably be unable to travel to the United States for up to the next six weeks.

Sharon, 75, underwent an hour-long operation to remove kidney stones in his urinary tract. The operation, pronounced a success, had been announced hours earlier when physicians urged the prime minister to undergo treatment.

Aides said Sharon was experiencing sharp pain on Sunday. He was diagnosed as having stones in his urinary tract. The stones were shattered by the use of ultrasound in a non-intrusive procedure. "The operation was successful without complications," an aide said. "He is feeling fine."

Israeli sources said the Bush administration has already rejected a key element in Sharon's withdrawal plan. This calls for Israelis evacuated from the Gaza Strip to resettle to Israeli communities in the West Bank, particularly in the Jerusalem area.