A wave of violence across Afghanistan killed 10 people, including a French commando, with militants using everything from roadside bombs to explosives hidden in a clock to subvert landmark elections on Sunday, officials said.

Despite the violence, there were no major disruptions in the voting, though some polling centers opened late because of security fears, chief electoral officer Peter Erben said.

Afghanistan goes to polls

The fiercest fighting occurred in eastern Khost province, near the border with Pakistan, leaving three militants and two policemen dead and one US service member wounded, police and the US military said.

Dozens of suspected Taliban rebels came across the mountainous border from Pakistan to attack a police checkpoint, triggering a three-hour gunbattle, said local police chief Gen Mohammed Hayub Hashini.

The survivors fled back across the frontier after the fighting.

Facts and figures about Afghanistan's election

In a second attack on the border, a French special forces soldier was killed and another was seriously wounded when their vehicle struck a mine while patrolling in the south, the Defense Ministry in Paris said.

In the capital, Kabul, two rockets hit a United Nations warehouse near an election office being used for media conferences, wounding a local staff member, said UN spokesman Adrian Edwards.

In a desert just north of Kabul, a large clock was found packed with explosives near a voting centre. Local officials said militants had tried to smuggle the clock into the polling place, but had been prevented by tight security.