Forty-five countries attended initial technical meetings for potential troop contributors, and the UN is hoping there will be announcements of troop commitments at a formal meeting on Thursday.

A senior UN official said there appear to be a number of reasons for the absence of any troop commitments.

France, which is expected to lead the force, has not yet made an announcement though it has sent a colonel to New York to discuss the shape and size of the expanded U.N. force, known as UNIFIL. France also sent a five-man military engineering team to Lebanon to evaluate the state of roads in the south and determine what Lebanese troops need to deploy there, the French Foreign Ministry said.

U.N. officials and diplomats said questions about the mandate for the force and whether it would be required to disarm Hezbollah fighters were also holding up troop commitments.

"We will be very happy if France agrees to provide a significant contribution that will provide the backbone of the force," Annabi said.

At Thursday's meeting, potential troop contributors will be given drafts of the rules of engagement for the force. The rules include using "forceful means" against anyone trying to prevent the UN peacekeepers from doing their job, the senior UN official said.

The U.N. officials and diplomats spoke on condition of anonymity because the meetings and planning are private.

While the foreign ministers of France, Turkey, Pakistan and Malaysia were expected in Beirut on Wednesday, mostly likely to work out details of assembling the 15,000-strong UN force, Israeli Foreign Minister Tzipi Livni was heading to New York.

She is expected to meet Secretary-General Kofi Annan to discuss the importance to Israel of a speedy deployment of the UN force, Foreign Ministry spokesman Mark Regev said.

Israel wants to ensure that a Hezbollah-free zone is created quickly in the south, and "to make sure that the international arms embargo on Hezbollah is implemented," he said.

Once the Lebanese army controls the south and all Israeli troops have pulled out, the government will then need to implement a September 2004 resolution calling for the disarmament of all militias, including Hezbollah, the senior UN official said.

The Lebanese government is supposed to do the main job, with support from UNIFIL, but some countries including France have made clear they will not disarm Hezbollah fighters.

Hezbollah leader Sheik Hassan Nasrallah has said he was open to dialogue about Hezbollah's weapons at the appropriate time, but suggested Monday that some Lebanese politicians were rushing to disarm the militant group.