Israel and Lebanon made no apparent progress today in setting an agenda for their negotiations.

After more than six hours of deliberations mainly confined to the chiefs of the Israeli, Lebanese and U.S. negotiating teams and two brief formal plenary sessions, U.S. Embassy spokesman John Reid announced: "We will continue our efforts to reach agreement on the agenda for the negotiations during our next meeting on Thursday, Jan. 6, at Qiryat Shemona, Israel."

Today's session, the third round in the tripartite talks, was held at the Lebanon Beach Hotel in this suburb five miles south of Beirut. The meetings have alternated between Khaldah and Qiryat Shemona.

The chief Lebanese negotiator, Antoine Fattal, told reporters that many obstacles remained but that he hoped a formula to which both the Lebanese and the Israelis agreed would be reached soon. Fattal said he sensed "flexibility" on technicalities on the part of the Israelis. "There was no intransigence," he said, "but a concentration by the Israeli side on normalization between the two countries."

This summed up the main disagreement on the points of the agenda: Lebanon insists that the talks center on a timetable for withdrawal of Palestinian, Syrian and Israeli forces from Lebanon, while the Israelis are insisting on giving top priority to normalization of their relations with Lebanon.

The Voice of Lebanon, the radio of Lebanon's Christian Phalangist Party, quoted delegates as saying today's session was devoted to "semantics." The two sides differ over what to call the disputed agenda item. Israel was reported to have suggested the alternative term of "good neighborly relations," while Lebanese delegates argued that "framework for future ties" was more suitable.

Lebanon's Fattal proposed that if agreement on an agenda proved impossible, the delegations could be "induced to start analyzing the heart of the problem" and probing substantive issues.

Israeli Foreign Ministry spokesman Avi Pazner, however, said Israel preferred to have a set agenda for coming talks. Both Fattal and Israeli delegates said it was normal for the start of any negotiations to be "slow."

In the northern port of Tripoli, meanwhile, violence between pro-Syrian and anti-Syrian Moslem militias intensified after two days of pitched battles that left at least 20 dead and 50 wounded. Residential areas were devastated by the ferocity of the clashes and power lines were knocked out, plunging the city into a total blackout.

The Syrian-backed Alawite fighters, better known as the "Pink Panthers," are entrenched in Tripoli's Baal Mohsen quarter, while their opponents, including Sunni Moslem fundamentalists, are deployed in the neighboring Bab al Tabbaneh quarter. The two groups have been vying for control of the largely Sunni city for over a year.