Israel continued to pound targets in southern Lebanon Friday, while Hezbollah fired a new type of rocket that reached deeper into Israel than any others in the previous 17 days of fighting.

As the conflict raged on, the United Nations withdrew unarmed observers from their posts along the Israeli-Lebanese border.

The decision comes three days after four UN observers were killed when an Israeli air strike destroyed their post near the eastern end of Lebanon's border with Israel.

"These are unarmed people and this is for their protection," UNIFIL peacekeeping force spokesman Milos Struger told reporters.

The 50 unarmed observers have been moved to less strategic posts that offer protection with 2,000 lightly armed UN peacekeepers.

Hezbollah's new rockets are the Khaibar-1, named after a famed battle between Islam's prophet Muhammad and Jewish tribes in the Arabian peninsula. Five rockets landed in the northern Israeli town of Afula, about 50 km from the border, causing alarm but no injuries.

Guerrillas on Friday also fired nearly 100 smaller rockets at several northern Israeli towns, the Israeli army said.

Meanwhile, Israeli warplanes continued to pound Lebanon Friday -- firing scores of missiles and reducing buildings to rubble across the southern part of the country.

Late in the day the army reported it killed 26 Hezbollah guerrillas in the fight for the southern town of Bint Jbail

Israeli artillery also hit a convoy evacuating villagers from southern Lebanon, wounding a journalist and a driver.

An AP photographer in the convoy said the explosion occurred as the group of ambulances, evacuees and journalists was returning from the village of Rmeish, where it had picked up residents trapped there by the bombings.

Another air strike flattened a house in the village of Hadatha, and six people inside were believed dead or wounded, the Lebanese state news agency reported. Hezbollah's al-Manar TV said all six were dead.

Aid agencies warn of crisis

Aid agencies warned Friday that aid workers were finding it impossible to get medical supplies and food safely to isolated villages in southern Lebanon due to the Israeli bombardment.

World Food Program spokesman in Beirut, Robin Lodge, said the UN food aid organization had been unable to move supplies to villages in the south.

"For security reasons we are not able to get to the areas south of Tyre," he said. "We are keenly aware of the needs."

The UN humanitarian chief, Jan Egeland, called Friday for a three-day truce between Israel and Hezbollah. He said it's necessary to evacuate trapped civilians and replenish supplies to areas cut off by the fighting.

"There is something fundamentally wrong with a war where there are more dead children then armed men," he said. "It has to stop."

At least 443 people have been killed in Lebanon in the fighting, most of them civilians, according to an official count Thursday. Lebanon's health minister estimated that as many as 600 Lebanese civilians have been killed, including victims buried in rubble.

According to the Israeli army, 33 soldiers have died in the fighting, and Hezbollah rocket attacks on northern Israel have killed 19 civilians.

Israel reports having killed about 200 Hezbollah guerrillas, but Hezbollah has reported only 35 casualties.

Environmental crisis hits Beirut

Meanwhile, the conflict has created an environmental crisis in Beirut's beaches, as water surrounding the capital's coast has turned black from oil.

More than 110,000 barrels of oil spilled out of the Jiyeh power plant two weeks ago, after an air strike by Israeli warplanes.

The spill has affected about 128 kilometres of shoreline, and some fishermen said their livelihoods have disappeared.

"I have nothing but the sea," fisherman Salim Yazmanji, 32, told AP.

He said for every nine-metre stretch of beach, it's not unsual to see 100 fish dead from the oil.

"If you take the sea from a fisherman, he will die, like the fish," Yazmanji told the news agency.

Workers were expected to receive supplies Friday to start cleaning the spill, but the conflict will likely make the operation impossible.

Israel launched its offensive in Lebanon on July 12, after Hezbollah guerrillas captured two Israeli soldiers in a cross-border raid.

Israeli forces opened an earlier offensive in the Gaza Strip on June 28, three days after Hamas militants attacked an Israeli army post, killing two soldiers and capturing another one.

Hezbollah and Hamas have both demanded the release of Hezbollah and Palestinian prisoners in return for freedom for the three Israeli captives, but Israel's government has refused.

With files from the Associated Press