An Afghan official says an insurgent ambush has killed four soldiers in the country's western Farah province.

Farah provincial spokesman Fawad Askari said another four were wounded Saturday when an Afghan National Army foot patrol came under attack along the region's main highway.

Insurgents frequently launch attacks on and around the highway, which is a main trade route through the province.

There was no immediate claim of responsibility.

The Taliban have escalated attacks in recent months as they try to take advantage of the withdrawal of foreign troops, who handed over security for the country to Afghan forces two months ago.