An Israeli air strike killed at least 33 civilians in northeastern Lebanon on Friday and Hezbollah fired scores of rockets into Israel in an escalating conflict that world powers have failed to halt.

Casualties were ferried to nearby Syria after the raid near Qaa in the Bekaa Valley. Bombs hit a depot where farm workers, many of them Syrian Kurds, were loading fruit onto trucks, security sources said. About 10 people were also wounded.

Earlier, Israeli jets destroyed four bridges on the main coastal highway north of Beirut, disrupting efforts to aid civilians displaced or trapped by the conflict in Lebanon.

With no action to end the 24-day-old war emerging from the United Nations, fierce fighting raged in the south as Israeli troops tried to expand seven small border enclaves they control.

Hezbollah guerrillas fired more than 100 rockets into northern Israel, killing two people and wounding several, police and medics said.

The bombing of bridges in the Christian heartlands north of Beirut cut off the main coastal highway to Syria.

"It's really a major setback because we used this highway to move staff and supplies into the country," said Astrid van Genderen Stort of the UN refugee agency UNHCR. "If we don't have new material coming in, we will basically be paralysed."

In Geneva, WFP spokeswoman Christiane Berthiaume said the coast road to Syria was an "umbilical cord" for aid supplies.

"We absolutely have to find other entry points, by sea or by air, to get aid into Lebanon," she added.

Israel said the bridges had been destroyed to prevent Syria from rearming its ally Hezbollah. "We are determined to stop this flow of arms to the Hezbollah and our attacks last night were to this end," an army spokesman said.

Israeli raids have already wrecked the main Beirut-Damascus highway, and imposed an air and sea blockade on Lebanon.

More than 150 Israeli air strikes hit targets across the south and artillery pounded border areas as Hezbollah tried to stop new Israeli incursions near Markaba and a strategic hill near the coastal town of Naqoura, security sources said.

"The thuds of explosions are continuous... It is one of the worst days (of fighting)," one source said.

Hezbollah fighters killed two Israeli soldiers and wounded two near Markaba, Israel's army said. Al Arabiya television said five Israeli soldiers had been killed. Israeli media said seven Hezbollah guerrillas had also died in the battle.

Blair sees 'critical days'

Israel, which has put more than 10,000 troops into Lebanon, says it has carved out a zone containing 20 villages 6-7 kilometres from the border and the defence minister has ordered the army to prepare for a possible push further north.

British Prime Minister Tony Blair delayed the start of his holiday on Friday to work on a UN ceasefire for Lebanon. "He thinks the next few days will be critical," a spokesman said.

US Assistant Secretary of State David Welch will visit Beirut on Saturday for talks with Lebanese Prime Minister Fouad Siniora on ways to end the war, Lebanese political sources said.

Welch will meet Siniora to discuss efforts at the United Nations to secure a ceasefire backed by an international force more robust than the UN peacekeepers already in south Lebanon.

The United States and France were to hold more talks to try to bridge their differences over a draft UN resolution.

Washington wants an international force in southern Lebanon immediately after a truce. France, a likely leader of the force, wants the troops to move in only after a permanent ceasefire.

Hezbollah chief Sayyed Hassan Nasrallah offered on Thursday to end cross-border rocket fire if Israel stopped attacking Lebanon, but said Tel Aviv would be hit if Israel bombed Beirut.

Israel has also launched an offensive in the Gaza Strip to recover another captured soldier and stop Palestinian rockets.

Israel killed three Palestinians in the Strip on Friday amid air strikes on militant targets that also wounded four people.

At least 164 Palestinians, more than half of them civilians, have been killed since Israel's Gaza offensive began on June 28.

Source: China Daily