TIBERIAS, Israel — Senior Israeli army officers were ordered last night to begin preparing for a new push 18 miles into southern Lebanon after Hezbollah rockets killed eight civilians in northern Israel.

Military officials said the next stage of the offensive aimed to secure territory up to the strategic Litani River.

Despite Israel’s intensive ground and air campaign, the latest barrage of Hezbollah rockets was one of the most lethal since fighting began more than three weeks ago.

As world powers worked to achieve unity on how to end the conflict, more than 130 rockets struck Israel within an hour in the late afternoon.

The deaths, in the cities of Acre and Maalot, raised to 27 the number of people killed by rocket fire from Lebanon.

“Israel will pursue Hezbollah until these murderous attacks cease and until quiet is restored to northern Israel,” an official in the office of the Prime Minister Olmert, David Baker, said.

Three Israeli soldiers were killed as Israel expanded its ground offensive in southern Lebanon, where seven brigades, or up to 10,000 troops, backed by artillery and helicopters, were involved in the campaign to drive Hezbollah out of the border area and create a buffer zone four miles deep along the 40-mile frontier. Israeli press and broadcast outlets speculated that three times as many troops would be called up for the second phase.

The army said that an anti-tank missile killed two soldiers, bringing to 39 the number killed by Hezbollah. It later said that a third soldier had been killed and that 15 had been wounded.

Channel 10 television said the army had carved out “a security zone” of 20 Lebanese villages up to four miles from the border. Other sources said the Israelis had won control of 11 villages along the frontier. Hezbollah sources said their guerrillas were defending border villages where civilians were still trapped by the fighting. Many of the fighters live in south Lebanon with their families.

Ranged against the Israeli forces are an estimated 2,000 to 3,000 fighters armed with assault rifles and shoulder-fired rockets. Israel says it has killed 300 to 400 guerrillas and Lebanese officials have put the figure at 500.

Israeli aircraft renewed attacks on Beirut for the first time in more than a week and continued their wide-ranging bombing campaign, including targets on Lebanon’s northern border with Syria and in the eastern Bekaa Valley.

Witnesses said that at least four missiles hit the southern Beirut Shiite suburb of Dahieh, which has been repeatedly shelled.

Lebanese security officials said a missile crashed into the two-story house in Taibeh, killing a man, his wife, and his daughter and that Israeli bombs had struck an ambulance working for an Islamic group in Nabatiyeh.

Prime Minister Siniora of Lebanon said the fighting had killed 900 people in Lebanon and wounded 3,000.