A suicide attack hit a NATO patrol in eastern Afghanistan on Wednesday, killing three coalition service members, the international military force said, while Afghan officials added that a civilian was also killed in the bombing.

Hours later on the other side of the country, a roadside bomb hit a bus, killing at least three people, a witness said. Many wounded passengers were trapped in the bus by a fierce battle between insurgents and Afghan police that raged most of the day.

The Taliban quickly claimed responsibility for the bombing of the NATO patrol in Kunar province, an eastern stronghold of the insurgency that lies along the volatile border with Pakistan where militants have hideouts.

The attack emphasized the insurgency's continued ability to wreak violence despite fierce efforts by the Afghan government and international forces to wipe out their leadership.

In Kunar, two attackers wearing suicide vests detonated their explosives as a NATO foot patrol passed by the headquarters of the provincial government, provincial police chief Ewas Mohammad Naziri said.