BEIRUT, Lebanon — Hezbollah fighters battled Israeli commandos who landed near the militants' stronghold deep inside Lebanon early Saturday, killing one soldier, in the first apparent large-scale violation of the U.N.-brokered cease-fire between the sides.

Hezbollah said its guerrillas foiled the raid after a gun battle, and the Israeli army said one soldier was killed and two were wounded, one seriously.

Witnesses said Israeli missiles destroyed a bridge during the raid, and Lebanese Prime Minister Fuad Saniora called the military action a "flagrant violation" of the cease-fire, which took effect Monday following 34 days of fighting.

The Israeli army said the special forces operation aimed "to prevent and interfere with terror activity against Israel, especially the smuggling of arms from Iran and Syria to Hezbollah." It said the commando team completed its mission.

The army said such operations would be carried out until "an effective monitoring unit" of Lebanese or multinational troops was in place.

"If the Syrians and Iran continue to arm Hezbollah in violation of the (U.N. cease-fire) resolution, Israel is entitled to act to defend the principle of the arms embargo," Israeli foreign ministry spokesman Mark Regev said.

Hezbollah TV and Lebanese security officials said Israeli helicopters dropped off a commando team outside the village of Boudai west of Baalbek in eastern Lebanon.

The officials, who spoke on condition of anonymity because they are not authorized to release information to the media, said the Israelis apparently were seeking a guerrilla target in a nearby school but had no other details. The officials also reported heavy overflights of Israeli jets.

Lebanon's foreign minister said he immediately informed a visiting U.N. delegation of Israel's violation.

Such a bold operation risked scuttling the fragile cease-fire and suggested Israel was going after a major target near Baalbek — perhaps to rescue two Israeli soldiers snatched by Hezbollah on July 12, or to try to capture a senior guerrilla official to trade for the soldiers.

Hezbollah has said it wants to exchange the two soldiers for Arab prisoners, but the U.N. cease-fire resolution demands Hezbollah unconditionally release the soldiers.

Local media said Sheik Mohammed Yazbeck, a senior Hezbollah official in the Bekaa and a member of the Shura council of the group, may have been the target. Yazbeck is a native of Boudai.

Israeli troops have killed several guerrillas who Israel said threatened its troops in south Lebanon since the cease-fire, and warplanes have flown over the country. But the cease-fire allows military action in self-defense, and the commando raid was by far the most serious incident since Monday.