UNITED NATIONS — A U.N. team sent to mediate in the Israeli-Lebanese conflict hit a snag yesterday when President Assad of Syria said one of the team’s members, U.N.envoy Terje Roed-Larsen, would not be welcome in Damascus.

As late as last night it was not clear whether Syria would remove the condition, opening the way for a meeting between the Baathist regime and Secretary-General Annan’s three envoys.The U.N. team was scheduled to return Turtle Bay tonight for a briefing with the Security Council tomorrow. Mr. Annan also is scheduled to meet Secretary of State Rice in New York tomorrow.

Syria’s rejection of the U.N. team’s most experienced diplomat came a day after President Bush was caught by an open microphone berating the secretary-general and then saying, “What they need to do is get Syria to get Hezbollah to stop doing this sh—, and it’s over.”

Damascus has presented Mr. Annan with a serious challenge, a diplomat familiar with the mediation team’s work told The New York Sun, speaking on condition of anonymity. But another Turtle Bay-based diplomat said a solution was discussed late last night that might allow the team to stop in Damascus after all.

Mr. Annan has called for an immediate cease-fire and, along with Prime Minister Blair, is promoting a plan to deploy a new multinational “stabilization force” in southern Lebanon.

The three-man team that Mr. Annan dispatched to the region last week met in Jerusalem yesterday with Foreign Minister Tzipi Livni. Later, borrowing a well-honed White House tactic, Prime Minister Olmert arrived for an unscheduled talk as his top aides conducted a discussion with the U.N.representatives.

Ms. Livni told the press after the meeting that Israel is not ruling out the possibility of an international force in southern Lebanon. During a briefing for Israeli diplomats, however, Mr. Olmert said the idea “is a good headline, but there is nothing behind it,” Israeli press outlets reported.

Both Mr. Olmert and Ms. Livni said that regardless of the diplomatic efforts — which might include a visit by Ms. Rice as early as next week — Israel will not end its military operations against Hezbollah before several conditions, including the group’s disarmament, are met.

Israeli military officials said yesterday that they have been able to wipe out 50% of the terrorists’ missile launching capacity since the operations began last week. But they were quick to add that the mission is far from over.”In my experience, the last 50% is the most difficult part,” the chairman of the Labor Party at the Knesset, Ephraim Sneh, told the Sun.

Mr. Sneh, a one-time top military commander on the Lebanese front, added that in his opinion “there is no other choice but to enter Lebanon, in the next few days, with ground forces” to disarm Hezbollah. He was skeptical of a multinational force, he added.

“Fighting terrorism requires motivation,” Mr. Sneh said. “What would motivate a French soldier, lying in an ambush, on a cold winter night, in southern Lebanon?” He said a Lebanese soldier, aware that his country’s future and independence depend on ending Hezbollah’s control of the country, would be much more effective.

The U.N. mediation team is led by the Turtle Bay-based adviser Vijay Nambiar. Its other members are Mr. Annan’s special envoy to the Middle East, Alvaro de Soto, and Mr. Roed-Larsen. The latter two have often clashed on several issues related to the region, and several U.N. officials have considered Mr. Roed-Larsen too sympathetic to Israeli causes in recent years.

A U.N. spokesman, Farhan Haq, announced yesterday that the team would return to New York, saying the envoys have to brief the Security Council. When the team’s trip was announced last week, however, spokesmen said Mr. Annan’s representatives were scheduled to visit Egypt, Israel, the “occupied Palestinian territories,” Lebanon, and Syria. As of late last night, Damascus was the only missed stop on the itinerary.

“It is not excluded that the team might later return to the region,” Mr. Haq told the Sun yesterday. He added that the envoys might still visit Damascus. The diplomat who spoke to the Sun said the team is barred from entering Damascus unless Mr. Roed-Larsen is not among them.

The Norwegian Mr. Roed-Larsen, a veteran Middle East mediator, currently serves as Mr. Annan’s special envoy for the implementation of Security Council resolution 1559, which calls for all foreign troops to leave Lebanon, as well as for the country’s militias to disarm and Lebanese troops to be deployed throughout country.

Mr. Roed-Larsen has made several comments that have angered the Assad regime, and has documented transfers of weapons to Hezbollah’s strongholds and Palestinian Arab camps from Syria. In April, Mr.Annan reported to the council, based on Mr. Roed-Larsen’s findings, that Iran and Syria have”ties”to Hezbollah, in violation of resolution 1559.

Separately, a former U.N. investigator of the 2005 assassination of the Prime Minister Hariri of Lebanon, Detlev Mehlis, also pointed to Tehran and Damascus yesterday. “Hezbollah would certainly not risk taking the kind of action it has without having Syria’s approval,” he told Germany’s Deutsche Welle.