Israel, still threatening to attack, today weighed proposals for a Palestinian surrender that officials said hold out the hope for a peaceful end to the siege of West Beirut.

Official sources stressed that many points of disagreement remain in the suggestions, reportedly relayed from the Palestine Liberation Organization through the Lebanese government to the United States and Israel. But they added that the overall impression from the day's contacts was that the PLO leadership is reconciled in principle to disarming and leaving Lebanon.

Those were the main conditions laid down by Israel's Cabinet yesterday. Until they are met, officials said, no other negotiations on Lebanon's future or Israeli withdrawal can begin. If the conditions are not met, they added, Israel remains poised for an all-out attack on Palestinian strongholds in West Beirut.

Suggestions relayed through U.S. special envoy Philip C. Habib via Washington were said to include several elements that, according to Israeli officials, are unacceptable to Prime Minister Menachem Begin's government unless it alters previous positions. These included PLO permission to retain small arms to administer and police Palestinian refugee camps in Beirut, that a PLO unit remain armed as part of the Lebanese Army and that Israeli forces withdraw several miles.

Begin, Sharon and Foreign Minister Yitzhak Shamir met this afternoon on the proposals relayed from Habib, officials said. A departure by sea rather than overland to Syria was approved, they said, but Israel was unlikely to agree to the guerrillas retaining small arms and continuing to police refugee camps.

"There are some elements that you can talk about," an official said, mentioning possible surrender routes out of Beirut as an example. "But the main message--they all must leave--is not negotiable."

Defense Minister Ariel Sharon depicted Israel's conditions--Palestinian surrender and the disarming and departure of all PLO fighters--as "a generous offer."

Another high Israeli official said, "I think we are showing magnanimity in allowing them to lay down their arms and leave Lebanon. We show magnanimity because it is in our nature to be magnanimous in this kind of situation."

Some opposition Labor Party members of parliament have voiced strong criticism of the government's conduct of the war. Former prime minister Yitzhak Rabin, the number two Labor leader, said last night that Sharon and Begin had so expanded Israel's war aims as to make them impossible to achieve.

[Meanwhile Israeli spokesman Uri Porat said Begin had written to President Reagan drawing his attention to remarks by Rep. Charles Wilson (D-Tex.) who spent two days last week touring the Israeli-occupied portion of Lebanon, Associated Press reported.]

[Wilson, in an interview on Israeli radio, said he had been "astonished" at the "universal enthusiasm with which the Lebanese welcomed the Israeli Army." He said Lebanese he spoke with--Moslems as well as Christians--had received the Israelis "almost like a liberating army."]

[While he was "not prepared to pass judgment in my own mind on the wisdom of the invasion," Wilson said, he was going to take back to Congress the message that the invasion "was good for the Lebanese" and that "the Lebanese themselves are glad it happened."]