Nineteen Israeli soldiers were killed Saturday during an expanded offensive in Lebanon, the army said, making it the highest one-day toll for the Jewish state since the war against Hezbollah erupted.

The deaths, which occurred in several battles in Lebanon throughout the day, brought to more than 100 the number of Israeli troops killed so far.

In its statement Sunday, the military also said that a five-member crew of a downed helicopter was missing.

The transport helicopter was shot down by Hezbollah guerillas. Only the crew were on board at the time, the army said.

On Saturday, more Israeli tanks and soldiers surged into southern Lebanon, reaching the Litani River and engaging in some of the heaviest ground combat of the monthlong war just hours after the U.N. Security Council adopted a cease-fire plan.

The leader of the Islamic militant group Hezbollah grudgingly joined Lebanon's government in accepting the U.N. resolution but vowed to keep fighting until Israeli troops leave and hand over territory to a muscular U.N. peacekeeping force intended to separate the antagonists.

Israel also signaled its intention to approve the plan, at a Cabinet meeting Sunday, and a senior official predicted fighting would stop Monday morning, but there was no slowing in the bloodshed.

U.N. Secretary-General Kofi Annan announced early Sunday that a cease-fire would take effect at 8 a.m. Beirut time Monday (1 a.m. EDT), saying both Israeli and Lebanese leaders agreed to the start time. In his statement, Annan called for an immediate halt to the fighting.

Israel was determined to batter Hezbollah until the end, while the guerrillas seemed to be fighting as fiercely as ever after a month of intense Israeli air, artillery and ground assaults.