Lebanese tanks and armoured troop carriers moved across the Litani River after dawn to replace withdrawing Israeli troops who had seized swathes of the border area during Israel’s devastating 34-day offensive on Lebanon.
While the Lebanese soldiers moved in, the UN worked on its troop deployment plan.
Initial plans for a French-led force stalled over concerns about its rules of engagement, but the UN’s Deputy Secretary General Mark Malloch Brown said that many issues appeared to have been overcome.
"We've had a lot of interesting offers this afternoon, some fairly firm, some conditional on seeing the rules of engagement and the concept of operations," he said after winding up talks between dozens of member states to thrash out the force's scope and composition.
"The show's on the road, we're in business, but there's a lot of work to be done in the coming days to meet the deadline that we insisted on in this meeting, which is that we have 3,500 additional troops deployed within 10 days."
The force will be charged with policing a fledgling ceasefire between Hezbollah and Israel after a month of fighting and will be followed by the full deployment of 15,000 peacekeepers as agreed under a UN-brokered ceasefire.
Much of the concern expressed by member states surrounded the force's rules of engagement, especially in relation to a potential confrontation with Hezbollah.
"Very much the issue is under what circumstances our troops have to engage in hostile offensive activities," Mr Malloch Brown said.
"This is a prudently designed rules of engagement which is not offensive in character but does call on you to robustly use force if it's necessary," he said.
France, which has strong historical links to Lebanon and has offered to command the expanded force, hesitated on whether to provide the backbone of the 15,000-man force, offering just 200 troops, far less than the UN was expecting.
Germany ruled out contributing ground troops but proposed sending a "maritime protection component" with its navy taking part in the future deployment, saying any moves hinged on the establishment of clear rules of engagement.
A UN source said Bangladesh, Indonesia, Malaysia and Nepal had each offered at least one battalion, and Denmark two warships.
In a sign of efforts to restore some semblance of normal life in Lebanon, two passenger planes landed in Beirut for the first time since Israeli fighter jets bombed the runways the day after the war began.
But despite urgent appeals from the European Union to lift restrictions on air and sea access to Lebanon, Israel insisted the measures would stay in force until all areas of south Lebanon it occupied had been handed over to Lebanese government troops and UN peacekeepers.
Thousands of families displaced by the conflict were still flocking south, although foreign aid groups voiced concern about getting emergency supplies to the most stricken regions through Israel's continuing blockade.
A total of 15,000 government troops are due to take control of the Hezbollah bastion in southern Lebanon, along with the promised expanded UN peacekeeping force.
The White House said the Lebanese government had committed to disarming Hezbollah, but that US President George W. Bush did not expect "overnight results."
A Lebanese army commander said the advance guard had deployed in 30 villages Thursday, including several next to the Israeli border.
"We should deploy within 24 hours along the Blue Line," the UN-demarcated border, said General Charles Shikhani, commander of the Marjayun area where troops hoisted their flag just seven kilometres from the frontier.
Israel said it had handed control of half the zones it was occupying to UN peacekeepers and that of the 30,000 troops who poured into Lebanon at the height of the war, all reserve units had now withdrawn.
Asked on a visit to New York how long it would take Israel to complete its withdrawal, Deputy Prime Minister Shimon Peres said: "The sooner the better. I would speak in terms of weeks -- maybe one week, two weeks."
Israeli army chief Dan Halutz had warned his forces could remain in the border region for months while the beefed-up international force deploys, despite the area having been a deadly quagmire for Israeli troops during a 22-year occupation until 2000.
France had called for safety guarantees for its soldiers before making further commitments beyond an initial 200 extra troops.
Defence Minister Michele Alliot-Marie warned the force's deployment could spell catastrophe unless its mission was clarified and a large number of Muslim countries were seen to be taking part.
Lebanese Prime Minister Fuad Siniora said the operation would stamp the government's authority on the south where Hezbollah had held sway since Israel ended its last occupation six years ago.
"There will be a single state... with the sole decision-making power, there will be no dual authority," he said. "There will be no off-limit regions for the army."
Hezbollah leader Hassan Nasrallah has vowed to keep fighting until the last Israeli soldier leaves Lebanese soil and so far rejected any moves to rid it of its weapons.
But Italian Prime Minister Romano Prodi, whose government is expected to give approval on Friday to the deployment of between 2,000 and 3,000 troops to Lebanon, received assurances from Mr Siniora that Hezbollah would cooperate with the expanded UN force, his office said.
Israel has warned of the risk of further fighting if Hezbollah keeps its weapons.
Lebanon's pro-Syrian President Emile Lahoud, however, said it was "shameful" to ask Hezbollah to disarm considering it was "the only force in the Arab world that was able to stand up to Israel".