"We have reached the 5.000 troops. The first phase of the UNIFIL deployment is now completed," said Alexander Ivanko, spokesman for the UN Interim Force in Lebanon.
Mr Ivanko said that the initial number of about 2,000 UNIFIL troops had been boosted to 5,000 by three new battalions from France, Italy and Spain.
A spokeswoman for Prime Minister Ehud Olmert said Israel intended to leave southern Lebanon once conditions agreed with UN Secretary General Kofi Annan, mainly the deployment of 5,000 international troops, were met.
Israeli forces have remained in southern Lebanon for more than a month after an August ceasefire came into effect ending the 34-day war between Israel and Shiite guerrillas, Hezbollah.
Israeli troops have gradually redeployed south of the volatile border as the French-led UNIFIL forces and the Lebanese army both assume control in southern Lebanon.
It’s the first time in decades that the Lebanese army had taken up positions in southern Lebanon.
Israeli army chief Dan Halutz was quoted as having said on Tuesday that Israeli forces would leave Lebanon by Friday, in time for the Jewish New Year.