Israeli warplanes attacked Palestinian strongholds in southern Lebanon for the first time in two years today in a massive punitive raid that gravely threatened the six-week-old cease-fire.

Following two days of Palestinian rocket attacks on the Israeli town of Nahariya in which three persons were killed, Israeli Phantom jets struck at suspected Palestinian positions around the Lebanese port city of Tyre, reportedly killing more than 60 persons and injuring nearly 100 others.

(The raid, deadliest ever along the tense border, was seen in Beirut as the likely beginning of a new cycle of violence in which the Palestine Liberation Organization hopes to force Arab governments to rally to its support, Washington Post special correspondent Joseph Fitchett reported. Story in Page A17.)

Lebanon's official news agency said tonight that the number of dead was expected to be more than 110 by the time rescue operations are completed.

Palestinian guerrillas replied with Soviet-made surface-to-air misiles but Israeli pilots were seen making deep dives and turns in the sky to avoid them. There were no reports to Israeli casualties.

The punitive air strikes represented a clear escalation of the war in southern Lebanon and a serious setback to the possible resumption of Middle East peace talks at Geneva.

Palestinian and Lebanese officials immediately charged that the Israelis had bombed civilian targets and that most of the victims were Lebanese rather than Palestinians. UPI reporter David Pearche, who was at Tyre during the bombing, said many of the victims were women, children and old men.

The Israeli chief of staff, Gen. Mordechai Gur, said the air strikes took place in the coastal area south of Tyre from Ras Bayyida, about five miles from the Israeli border, to Ras Shaidya, about 11 miles from the border, and ranging for about six miles inland.

Gur told reporters that all the targets had been carefully selected and that only Palestinian positions and troop concentrations were hit. He said that there were no civilians in the areas hit and that no Lebanese or Syrian positions were attacked.

It was difficult to believe that the strikes could have been as selective as described, however, given that Palestinian camps in that region often include women and children as well as fighting men.

Israel's intention, Gur said, was to strike with sufficient force to head off a cycle of attacks and counterattacks.

Since the Palestinian rocket attacks on Nahariya began on Sunday - an act Israel looked upon as on outright violation of the fragile cease-fire agreement modiated by the United States Israel had limited its retaliation to arillery bombardments Israeli ground action within Lebanon before the cease-fire had been restricted to helping Christian Arab forces within a few miles of the border.

Gur said today that although the cease-fire had been broken, the Israeli government had not decided to cnacel the trace. He said that he hoped today's air strikes would be "a one time action" and that the cease-fire could be presevered if the border area remained quiet.

The punitive raid coincided with the burial today of the victims of the Palestinian attack on Nahariya.

Last night Prime Minister Menahem Begin said in a speech: "Gone are the days when Israeli blood could be spilled without any reaction." But he added that the "last thing we want is war or bloodshed" and that he hoped the cease-fire could be preserved.

It could appear that by today's action Israel hopes that Syria and the United States will put pressure on the Palestinians to keep the peace along the border and that Israel can avoid the more drastic and dangerous step of a full-scale ground attack on Palestinian positions in Lebanon.

The situation here along the northern border remains vey tense with troops on full alert and there was considerable military activity. Military policemen were attempting to turn back reporters several miles from the frontier. If rocket attacks on Israeli towns continue, further military action cannot be ruled out.

Gur told reports that guerrillas of [TEXT OMITTED FROM SOURCE]