A NATO airstrike on militants planting a roadside bomb in eastern Afghanistan left five suspected insurgents dead, while a clash in the west killed another 10 militants, officials said Tuesday.

The airstrike happened as the group was spotted digging on the road and laying a roadside bomb in Bermel district, in Paktika province, late Sunday, said Sgt. 1st Class Dean Welch, a U.S.-led coalition spokesman.

Authorities retrieved the bodies, which were later handed over to village elders from Bermel, said provincial police chief Nabi Jan Mullahkheil.

Militants frequently use roadside bombs to target Afghan and foreign troops.

In western Farah province, a large group of insurgents attacked a government building in Bakwa district on Tuesday, sparking a four-hour battle that left a police officer and 10 suspected militants dead, said Ahmad Khan, a police officer.

Afghanistan is going through its most violent period since the U.S. invasion six years ago. More than 5,100 people — mostly militants — have died in insurgency-related violence in 2007, according to an Associated Press count based on information from Afghan and Western officials.