Israeli officials say a soldier has been killed and two others wounded in an Israeli commando raid deep into Lebanon.
The operation is the first major attack since a U.N. truce Monday ended 34 days of intense fighting between Israel and Hezbollah guerrillas.
An Israeli government spokesman said Israel acted to prevent Syrian and Iranian arms from entering Lebanon in violation of the U.N. ceasefire.
But Lebanon's defense minister said Saturday that his country could halt its deployment south of the Litani River unless the United Nations intervenes. Lebanon's prime minister called the raid a violation of the U.N. ceasefire.
Witnesses say Israeli helicopters dropped the commandos near the city of Baalbek, in eastern Lebanon. They say the commandos, disguised as Lebanese troops, drove toward Bodai, west of Baalbek, where they stormed a school and clashed with Hezbollah fighters.
Lebanese security forces said at least three Hezbollah guerrillas were killed in the firefight.
Local media say Israel may have been targeting a senior Hezbollah official who lives in the area.
Elsewhere, boats carrying 50 French soldiers landed near the U.N. peacekeepers' headquarters in southern Lebanon early today. The soldiers are the first reinforcement of U.N. peacekeepers in the region.
The United Nations hopes to deploy up to 3,500 troops within two weeks to help the Lebanese army control the southern portion of the country now dominated by Hezbollah militants.
Late Friday, U.N. Secretary-General Kofi Annan urged Israel and Lebanon to take what he called "painful steps" to secure peace in the region. He said the unconditional release of Israeli soldiers abducted by Hezbollah guerrillas is one of many measures still to be taken.
Some information for this report provided by AP, AFP and Reuters.