KABUL – A US soldier serving under NATO was killed in an insurgent attack in eastern Afghanistan, the force said Thursday.

The American soldier, who was part of NATO's International Security Assistance Force (ISAF), was killed in a rebel attack on Wednesday while on patrol, an ISAF statement said.

His death took to 460 the number of international soldiers killed in Afghanistan so far this year, the deadliest of an eight-year anti-insurgency campaign being fought by about 100,000 NATO and US-led troops.

More than half of this year's dead have been from the United States, the biggest troop contributor to the war, now into a ninth year.

The latest fatality came one day after the killing of five British soldiers by a "rogue" Afghan policeman in southern Helmand province, where most British soldiers are based.

Afghan authorities and ISAF have launched an investigation into the incident in Taliban-troubled Nad Ali district, where a manhunt is underway for the attacker, the government said.