KABUL, Afghanistan - A suicide bomber with explosives strapped to his chest blew himself up yesterday in a crowd of laborers waiting outside a U.S. military base in eastern Afghanistan, killing as many as 10 people.

Elsewhere, Afghan and NATO forces killed 12 insurgents in a five-hour gun battle, and a Taliban ambush left nine police dead in the south, officials said.

The suicide bomber struck as hundreds of Afghan workers lined up to enter the base, known as Camp Salerno, outside the city of Khost, Gov. Jamal Arsalah said.

Arsalah, who saw the aftermath of the explosion, said 10 men were killed and 14 injured. The NATO-led force, which includes the U.S. base, said eight Afghans, including two policemen, were killed and five wounded. No U.S. or NATO troops were injured in the blast.

The NATO-led International Security Assistance Force said the attacker detonated an explosives-filled vest when he reached the point where people entering the base were searched.

Suicide attacks have become more frequent as Taliban extremists have intensified their insurgency against the Afghan government and foreign troops backing it. According to U.S. military figures, there were 139 suicide attacks in 2006, up from 27 in 2005.

Yesterday's was the deadliest since Sept. 30, when an attacker killed 12 people outside the gates of the Interior Ministry in Kabul.

Meanwhile, Gulbuddin Hekmatyar, an Afghan warlord whose fighters operate in eastern Afghanistan's mountains alongside Taliban and al-Qaeda remnants, said the United States faced a Soviet-style humiliation in the country.

"Everyone knows that the American aggressors are faced with defeat in every part of the country," Hekmatyar said in a recording obtained by the Associated Press in Pakistan. "They are preparing to leave, like the Soviet troops."

The 24-minute recording was the third from Hekmatyar to surface this month.

In southern Afghanistan, Afghan and NATO-led forces battled insurgents for nearly five hours, leaving 12 suspected Taliban dead and four wounded, according to Uruzgan province's police chief, Gen. Mohammad Qasem. Two policemen were killed and 10 wounded, he said.

Suspected insurgents also ambushed a border police patrol on the road from Kandahar to Uruzgan, killing nine policemen, Qasem said.