Afghan police and international military forces killed 10 militants in southern Helmand province overnight, the interior ministry said on Saturday.

Violence has surged in Afghanistan with some 5,000 people, including more than 2,000 civilians, killed last year alone, the United nations says.

In the latest incident, insurgents ambushed police and foreign soldiers in Naad Ali district after the joint force had arrested three men trying to plant a roadside bomb, the ministry said in a statement.

As a result, 10 insurgents were killed, it said. No Afghan police or foreign soldiers were wounded in the incident.

Foreign military officials in Afghanistan say they expect a spike in violence as new troops are sent to the war-torn country to fight a renewed Taliban insurgency.

President Barack Obama is expected to sign on orders to send thousands of new U.S. soldiers to Afghanistan this year that could see an almost doubling of U.S. forces in the country to some 60,000 soldiers.

Some 3,500 new U.S. troops arrived last month with the majority of them stationed around the capital.