Hezbollah leader Sheik Hassan Nasrallah said Saturday that the Islamic militant group will abide by a U.N. cease-fire resolution but will continue fighting as long as Israeli troops remained in south Lebanon.

A senior Israeli government official, speaking on condition of anonymity, said Israel will halt its war in Lebanon at 7 a.m. (midnight ET) on Monday. Israel’s Cabinet was to endorse the U.N. cease-fire resolution on Sunday.

Nasrallah grudgingly accepted the cease-fire plan in a televised address as the Lebanese Cabinet was in session to vote on whether to agree to the U.N. resolution. Hezbollah has two ministers in the government.

“We will not be an obstacle to any (government) decision ... but our ministers will express reservations about articles that we consider unjust and unfair,” he said.

Hours later, Israel Radio reported Israeli army units reached the Litani River, less than 24 hours after the government ordered an operation to march toward the river in a final push against entrenched Hezbollah guerrillas.

The units were part of a massive force that flooded into Lebanon, trying to seize as much territory as possible before a U.N. cease-fire comes into effect. The objective was to control southern Lebanon up to the Litani River, about 18 miles from the Israeli border, before handing over the area to the Lebanese army and U.N. troops.

The U.N. Security Council adopted the resolution seeking a “full cessation” of violence between Israel and Hezbollah on Friday, offering the region its best chance yet for peace after a month of fighting that has killed nearly 900 people and inflamed Mideast tensions.

The resolution, adopted unanimously, authorizes 15,000 U.N. peacekeepers to help Lebanese troops take control of south Lebanon as Israeli forces that have occupied the area withdraw.

The Shiite cleric said Hezbollah rocket strikes on northern Israel would end when Israel stopped airstrikes and other attacks on Lebanese civilians.

Some of the heaviest fighting of the war raged Saturday as Israel sent an avalanche of military power into Lebanon, dispatching thousands of troops and columns of armor into the rocky hills just north of its border.

More fighting predicted
Nasrallah called continued resistance to the Israel offensive “our natural right” and predicted more hard fighting to come.

“We must not make a mistake, not in the resistance, the government or the people, and believe that the war has ended. The war has not ended. There have been continued strikes and continued casualties,” he said.

“Today nothing has changed and it appears tomorrow nothing will change,” he said.

Meanwhile, Israeli helicopters flew hundreds of commandos into the Hezbollah heartland and warplanes staged wide-ranging airstrikes.

Airstrikes killed at least 19 people in Lebanon on Saturday, including 15 in one village, and Hezbollah rockets wounded at least five people in Israel. Long columns of Israeli tanks, soldiers and armored personnel carriers streamed over the border.

More than 50 helicopters ferried Israeli commandos into southern Lebanon in what was called the biggest such operation in Israel’s history. It was part of the push to drive Hezbollah fighters behind the Litani River, about 18 miles from the border, before the truce.

But Hezbollah fought back hard. Israel said dozen of its soldiers were wounded in the expanded offensive, which has tripled the Israeli troop strength in southern Lebanon.

The Islamic militant group said its fighters killed seven Israeli soldiers and destroyed 21 tanks. Israel said its troops had killed 40 Hezbollah guerrillas over the previous 24 hours.

Military campaign through the weekend
The Israeli Cabinet was expected to approve the cease-fire Sunday, but Israel appeared ready to keep up its full-scale military campaign until the U.N. plan worked its way through the region’s political leadership over the weekend.

Israel’s army chief, Lt. Gen. Dan Halutz, said Israel expected to fight for another week despite the cease-fire deal. He said Israeli forces — apparently about 30,000 soldiers now — would stay in Lebanon until an international force arrived.

Israel has demanded an airtight buffer zone and wonders if U.N. and Lebanese forces are up for the task. A small U.N. military presence — now about 2,000 observers — has been in Hezbollah-controlled southern Lebanon since 1978 and has been overwhelmed by the Islamic militant group’s rising power, aided by Iran and Syria.

Israeli missiles slammed into the southern Lebanon village of Rachaf, about 10 miles from the Israeli border, killing at least 15 civilians, security officials said. Israeli ground forces also fanned out across southern Lebanon hunting for Hezbollah rocket batteries that have fired unending salvos across the border.

Three people also were killed in strikes on Kharayeb, and a Lebanese soldier was killed in an air raid near an army base in the Bekaa Valley, officials said.

In Sidon, a coastal city between Beirut and the Israeli border, Israeli bombs destroyed a power plant. Farther south, another power facility was hit near Tyre, knocking out electricity to the port, police said.

Last border post hit
On Lebanon’s northern frontier, Israeli airstrikes hit the highway leading to the Arida border crossing about a mile from the Mediterranean coast. It was the last official border post open for humanitarian convoys and civilians fleeing the country. The highway was impassable, but drivers tried to maneuver through ruts and ditches.

The only other exits from Lebanon are rugged pathways and back roads through deserts or mountains.

Israel seeks to block supply routes for Hezbollah and disrupt their mobility and has warned it would target any vehicles on the roads in southern Lebanon and along other main highways.

On Friday, an Israeli aircraft fired on a convoy of more than 600 civilian vehicles and others carrying 350 Lebanese police and soldiers who left the Israeli-occupied town on Marjayoun in southeast Lebanon. Police said three civilians and an army recruit were killed and 28 people were injured. The mayor of Marjayoun, Fuad Hamra, put the death toll at six.

Israel said the U.N. troops asked permission to lead the convoy, but it was denied. Previous groups were given permission and traveled unharmed, the Israeli military said.

Fighting ongoing in Hezbollah hub
Fighting continued in Hezbollah-held areas around Marjayoun, a strategic hub overlooking valleys used as Hezbollah rocket bases.

Israeli commando units and guerrillas engaged in close combat in a valley near El-Ghandourieh, about 10 miles southwest of Marjayoun, according to Lebanese security officials.

Other Israeli ground forces, backed by aircraft and drones, met stiff resistance as they tried to reach the Litani River.

Israel said its troops destroyed several rocket batteries and killed more than 40 Hezbollah fighters in the last 24 hours. The guerrilla group announced four deaths Friday and three Saturday.

After a morning free of Hezbollah rocket strikes in northern Israel, a barrage of 20 missiles at midafternoon injured two people in Amirim and three in Kiryat Shemona. Hezbollah had been averaging nearly 200 hits each day in the monthlong conflict.

The Litani is seen by Israel as a crucial boundary in its attempt to push back Hezbollah. Israel repeatedly has insisted that the proposed peacekeeping force cannot allow Hezbollah weapons south of the river.

But it will be nearly impossible to rid south Lebanon of the Islamic guerrillas, who are now in the Lebanese Cabinet and run clinics and other charities that are considered essential in rebuilding the region. Their ability to withstand the Israeli military assault has also made Hezbollah heroes across the Arab and Islamic worlds.