Israeli Defense Minister Ariel Sharon has admitted that the Israeli Army helped plan and coordinate the foray of Lebanese Christian militiamen into two Palestinian refugee camps that resulted in a massacre.
But Mr. Sharon denied any Israeli Army complicity in the massacre and refused a call for his resignation.
The Israeli government defeated by 48 to 42 votes a motion calling for establishment of an official commission of inquiry. Prime Minister Menachem Begin has refused such an inquiry despite requests by leading Israelis across all party lines.
The defense minister's bombshell, wrapped in steely language devoid of any self-criticism, contradicted repeated official Israeli denials over the previous five days that Israel had requested the Christian militia to enter the camps or had cooperated with them.
It also raised the prospect of continued political upheaval in Israel despite the government's survival and further angry repercussions abroad. Israeli Energy Minister Yitzak Berman resigned from the Cabinet Sept. 22 over Mr. Begin's refusal of an official inquiry, and other ministers will be watching carefully to see if a promised unofficial investigation takes place.
In addition, the opposition will continue to press for Mr. Sharon's resignation. The massacre has also aroused violent demonstrations in both Israeli Arab towns and in the occupied West Bank.
In another thunderbolt, the Israeli civilian administrator of the West Bank, Prof. Menachem Milson, who was the architect of the much-criticized occupation policy of Defense Minister Sharon, which was closely linked to the destruction of the Palestine Liberation Organization, in Lebanon, resigned Wednesday, calling the future of this policy into question.
Defense Minister Sharon's speech partly clarified some questions. But he also dodged unanswered questions about the massacre while leaving many loose ends hanging. Among them:
* What was Israel's involvement? Mr. Sharon said Israel had allowed Phalangist militia - Christian troops attached to the Lebanese Forces commanded by the late Bashir Gemayel - into the refugee camps, which Israeli troops surrounded. Their purpose: to ''comb and purify'' the area of Palestinian guerrillas who Israel believed had remained behind when the PLO was evacuated. It was stresssed in the coordinating meetings (with the Phalangists), Mr. Sharon said, ''that the action is against terrorists and must not harm civilians. . . .''
(Mr. Gemayel's Phalangists, bitter enemies of the Palestinians, had earlier been expected by the Israeli Army to clear PLO guerrillas out of west Beirut, but Mr. Gemayel refused in the interest of becoming president and reunifying Lebanon. In pursuing these goals he could no longer afford to be associated with intra-Lebanese bloodletting.)
Mr. Sharon said Israel let the Phalange do the job because it did not want to risk its own men. He said Israel fired flares to light up the camp area for the Phalange on Thursday night, the time when it is believed most of the killings took place.
Zeev Schiff, Israel's foremost military correspondent, reported on Tuesday that Mr. Sharon had ignored warnings from senior officers in Beirut about the danger of allowing the Phalange into the camps. Mr. Schiff wrote that Mr. Sharon himself gave the orders to the Phalange to go in.
* Why wasn't the killing stopped sooner? Mr. Sharon said that as soon as a senior officer on the spot reported suspicions about Phalange actions inside the camp, the Christian action was immediately ordered stopped. Yet journalists saw Israeli soldiers chatting with and giving water to Christian militimen around the camps as late as 6 p.m. Friday. And at 7 a.m. Saturday, foreign medical personnel were marched out of Gaza Hospital at the edge of the camp and taken through the camp, where they saw Christian militiamen rounding up scores of Palestinians, whose fate is still unknown.
All this happened within view of Israeli sighting telescopes trained on the camp from atop a seven-story headquarters at the camp's edge.
* Did Israeli soldiers know about the slaughter? Mr. Sharon insisted ''no soldier or commander of the Israeli Defense Forces took part in this terrible act.'' He said the Israelis knew little about what was going on because it was impossible to see from outside into the densely populated camp.
* There is no evidence that Israeli soldiers knew at the beginning of the carnage - some of which was done stealthily by ax and knife. But suspicions were clearly aroused by the length of the operation and quite possibly by actual sightings and by reported boasts of militiamen returning from inside the camp.
Opposition Labor Party leader Shimon Peres challenged Mr. Sharon, ''Where was your supervision? Where was your surveillance?''
Journalist Schiff noted that Phalangist leaders were not halted even after Israel had ordered them to cease firing by Friday morning.
* Who did it? Throughout his presentation Mr. Sharon referred to Phalangists , despite denials from President-elect Amin Gemayel that Phalange soldiers were involved. Mr. Sharon said that he and Maj. Gen. Amir Drori, chief of northern command, went to debrief the Phalange commanders involved, whom he did not name, but that the Phalangists refused to speak or even to admit their involvement.