By KATHY GANNON
Associated Press

KABUL, Afghanistan - Four Afghan security guards for a U.N. mine-clearing program were killed in a U.S. air assault, the United Nations said Tuesday, the first independent confirmation of civilian deaths since the airstrikes began.

Meanwhile, the ruling Taliban's envoy to Pakistan said Osama bin Laden, a target of the raids and the prime suspect in the Sept. 11 terror attacks in the United States, survived the bombings.

"He is alive, his health is very good and he is in Afghanistan," the ambassador, Abdul Salam Zaeef, said in an interview with CNN.

Bombing continued into the daylight hours for the first time, with strikes Tuesday on the Taliban stronghold of Kandahar after a second night of U.S. attacks targeting areas around Kabul and in the north, where an opposition alliance is battling the Taliban.

The U.N. mine-clearing agency's office on the edge of Kabul where the four security guards were killed was close to the Taliban radio transmission tower, a U.S. target. The target was knocked out in a U.S. raid Monday night.

U.N. spokeswoman Stephanie Bunker said the security guards, who were privately hired by a mine-clearing agency contracted by the United Nations, were spending the night in the office and hadn't been warned or told to relocate despite being near the communications tower.

"It was assumed they were safe where they were. Otherwise, they would have been relocated for sure," she said in the Pakistani capital, Islamabad.

"I think Afghans in general are aware of what's where," Bunker said, referring to potential targets. "We specifically instructed staff that if they feel endangered, they should abandon their duty situations."

She appealed for the U.S.-led coalition to take care not to hurt civilians. "People need to distinguish between combatants and those innocent civilians who do not bear arms," she said.

The United Nations evacuated international staff from Afghanistan at the outset of the crisis, but Afghan nationals working for U.N. organizations or groups under U.N. contract remained behind. The mine-clearing agency said last week it had suspended its operations.

The United States has emphasized that it is not targeting civilians in the attacks.

The Taliban claimed Tuesday that dozens of people have been killed in the U.S.-led raids, launched after weeks of fruitless attempts to get Afghanistan's rulers to hand over bin Laden. There was no independent confirmation of the claim.

"In this freestyle game, Washington is aiming firstly to hunt the sitting Islamic government in Afghanistan and then every committed Muslim in the name of terrorism," Zaeef told reporters in Islamabad.

Zaeef also said the Taliban's supreme leader, Mullah Mohammed Omar, was safe in the wake of the latest airstrikes. After the first raids late Sunday, an aide to the mullah said he had left his house only 15 minutes before missiles struck the building.

The envoy said there were no casualties among the ranks of the Taliban fighters.

"The Taliban are very strong," he said.

In Afghanistan's north, rebels continued to confront Taliban troops. The fighting came close to the border with neighboring Tajikistan at several points, said Russian border guards.

Kabul residents, meanwhile, spent another sleepless night amid the roar of explosions and the rattle of anti-aircraft guns. Farmer Adam Khan and his family of five were fleeing Tuesday on a truck piled high with belongings, heading out of the capital to an eastern district to escape more strikes.

They had been sleeping in their basement during the bombardment, he said. "All night the women and children were crying," he said. "They were very worried _ scared."

Targets in Monday night's raids included the airport in Kabul in addition to the hill where the radio transmission tower is located, according to the private Afghan Islamic Press agency in Islamabad.

In Washington, the Pentagon said all its planes returned safely.

There was no immediate confirmation that the aircraft carrying out Tuesday morning's raids were part of the U.S.-led coalition, though it appeared likely. Kandahar's location in the south of Afghanistan is far from any airstrips belonging to the anti-Taliban northern opposition, and the rebels' aircraft capability is limited.

The Taliban held the United States responsible for the latest strikes.

"This morning ... American aircraft made three strikes, but due to the use of anti-aircraft guns, these aircraft fled," Taliban spokesman Mullah Abdul Hai Muttmain told the Afghan Islamic Press. He said there was no immediate word on injuries or damage.

The strike on Kandahar, the seat of the Islamic Taliban militia that rules most of Afghanistan, came shortly after a lone, unidentified jet screamed through the early dawn sky over Kabul, dropping a bomb north of the city near the airport.

Early Tuesday, sitting in front of the mine-clearing agency's collapsed two-story building in Kabul's eastern Macroyan neighborhood, Mohammed Afzl wept. His brother was one of the four workers killed, and he waited for bulldozers to clear the rubble and remove the bodies. A fifth person was injured in the strike.

"My brother is buried under there," he said. "What can we do? Our lives are ruined."

As the raids began, lights went out in Kabul, and Taliban radio ordered people to close blinds, shut off lights and stay indoors.

U.S. Air Force Gen. Richard Myers, chairman of the Joint Chiefs of Staff, said the fresh bombardment Monday night was accompanied by a renewed air drop of humanitarian assistance. Humanitarian groups have said, however, that such airdrops are much less effective than road deliveries.

In the attacks, five long-range bombers _ a pair of B-2 stealth bombers flying from Whiteman Air Force Base in Missouri, and three B-1B's from the Indian Ocean island of Diego Garcia _ joined 10 strike planes launched from aircraft carriers in the Arabian Sea. They targeted air defense and other military targets across Afghanistan.

Two U.S. Navy ships, the destroyers USS John Paul Jones and USS McFaul, and one submarine launched a total of 15 Tomahawk cruise missiles.

Britain, which participated in the first wave of assaults Sunday, did not take part in Monday's follow-up, British Prime Minister Tony Blair said from London.

Before Monday's attacks began, President Bush vowed to be "relentless" in fighting terrorism "on all fronts." And in an indication the United States might eventually want to expand the military operation, Washington notified the U.N. Security Council on Monday that its counterterrorism attacks may be extended beyond Afghanistan.

Before the Monday night assault, the Taliban released a British journalist to Pakistani authorities. Yvonne Ridley, a reporter for a London newspaper, had been held for 10 days by the Taliban after sneaking into Afghanistan.

The Taliban are still holding eight international relief workers, including two Americans, detained in August for allegedly preaching Christianity in Muslim Afghanistan.

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Gannon contributed to this dispatch from Islamabad, Pakistan.