U.S. and Afghan troops killed or wounded more than two dozen Taliban fighters during a 21-hour battle in eastern Afghanistan that ended Saturday, military officials said.

The battle began Friday when U.S. and Afghan troops attacked a group of insurgents moving into position to attack a base in the eastern mountains of Kunar province, along the border with Pakistan, NATO's International Security Assistance Force said.

U.S. and Afghan forces received intelligence earlier Friday that insurgents were planning a mass attack, it said in a statement.

Kunar province is one of the most violent in the country. U.S. troops stationed there are routinely attacked by Taliban fighters and foreign insurgents allied with al-Qaida.

The U.S. and Afghan troops used mortars, artillery and helicopters to repel the attack. Fighter aircraft also dropped precision-guided bombs, ISAF said.

The mountainous terrain made it difficult to confirm the exact number of insurgent casualties but intelligence reports indicated that more than two dozen fighters were killed or wounded, ISAF said. No U.S. or Afghan forces were wounded or killed, and no civilian casualties were reported, it said.

Fighting in Afghanistan typically falls off during the winter, but sporadic engagements still take place. Last year, U.S. forces in the east saw suspected Taliban fighters move over the border en masse, and warplanes killed or wounded 130 of them.

Last year was Afghanistan's most violent since the 2001 ouster of the Taliban from power. More than 6,500 people — mostly militants — died, according to an Associated Press count based on official figures.