The attack is the latest targeting international troops, but there is no immediate word on casualties.

Local government spokesman Mubarez Zadran says a suicide car bomber struck the convoy as it rolled through Khost province's Mando Zayi district. He says foreign troops quickly cordoned off the road.

A spokeswoman for the international force, Lt Cmdr Katie Kendrick, confirmed the Khost explosion, but said the convoy apparently hit a roadside bomb. She said no casualties were immediately reported.

Insurgents have intensified attacks as 30,000 more American troops arrive to try to turn around the 9-year-old war and stabilise the Afghan government.(AP