KABUL - Afghan police backed by NATO-led troops have killed four criminal suspects in an operation prompted by a spate of kidnappings and robberies in western Herat province.

Police spokesman Rauf Ahmadi says the operation in Herat's Guzara district also resulted in the arrests of 15 other people suspected of involvement in criminal activities.

Police launched their sweep following the kidnapping last week of a doctor's son.

All medical workers in Herat city have been on strike for the last four days, demanding the government do more to provide security in the province that borders Iran.

The occasional kidnappings of foreigners in Afghanistan generally receive wide publicity. But Afghans are kidnapped for ransom almost daily and the problem goes mostly unreported.

Separately, 10 insurgents and two officers are reported to have been killed Monday in a clash with Taliban rebels in southern Uruzgan province.

On Sunday, four militants were killed in clashes with Afghan and foreign troops in the Korengal Valley in the eastern province of Kunar, a statement from the Defence Ministry said.

An Afghan soldier was killed in Kapisa province, just north of Kabul, the ministry said Tuesday.

Last year was the most violent year since the ouster of the Taliban from power in the U.S.-led invasion in 2001. More than 8,000 people died as a result of hostilities, according to a United Nations tally. An Associated Press count put the total of insurgency-related deaths at more than 6,500 -- most of whom were rebels.