During the clash, which ended only after U.S. forces called in airstrikes, a suicide bomber drove an explosives-laden truck toward the base's gates. It blew up when American troops fired on it.

More than 30 insurgents were killed in the battle in Zerok district of Paktika province, said Hamidullah Zawak, the provincial governor spokesman. Seven U.S. and two Afghan troops were wounded, a U.S. military spokesman said.

The multi-pronged attack near the Pakistan border is hundreds of miles (kilometers) from the massive Marine assault in southern Afghanistan and underscores the militants' ability to inflict casualties on the over-stretched U.S. forces as they widen their battle against the Taliban, who have made a violent comeback following their initial defeat in the American-led 2001 invasion.

Responding to the deteriorating security situation, President Barack Obama's administration has ordered 21,000 additional troops to Afghanistan and expects the total number of U.S. forces there to reach 68,000 by year's end. That is double the number of troops in Afghanistan in 2008 but still half as many as are now in Iraq.

As part of the new strategy, 4,000 Marines poured into volatile Helmand province on Thursday in the biggest U.S. military operation in Afghanistan since 2001, trying to cut insurgent supply lines and win over local elders.

Also in the south, a roadside bomb Saturday killed seven policemen in Kandahar province, the Interior Ministry statement said. Another two Afghan soldiers died in a separate blast in Helmand province's Musa Qala district also Saturday, the Defense Ministry said.

In the eastern attack, an insurgent drove a truck filled with explosives and gravel toward the gates of the U.S. coalition base, Zawak said. When the driver did not heed warnings to stop, troops opened fire on the truck, which exploded, he said.

The blast happened in the middle of a rocket and mortar fire attack on the base, which killed two U.S. troops and wounded seven other American soldiers, said Spc. April Campbell, a U.S. military spokeswoman.

The clash lasted for two hours before U.S.-called airstrikes that ended the fight, Zawak said.

Two Afghan soldiers were also wounded. The base housed both U.S. and Afghan soldiers.