The election is the latest step in a US-led process to bring democracy to the impoverished and deeply conservative Muslim country ravaged by 30 years of war and gripped by a brutal nine-year Taliban insurgency.

It comes at a pivotal time for 144,000 US-led NATO troops trying to implement a counter-insurgency strategy to reverse increasing Taliban momentum and allow American troops to start leaving next year.

Insurgents fired a rocket near the NATO mission's central Kabul headquarters shortly before polls opened at 0230 GMT, but no casualties or damage were reported, a spokeswoman for the alliance said.

The White House warned Friday of "serious security concerns" for the vote, the second since a US-led invasion in late 2001 ousted the hardline Islamist Taliban regime.

The Taliban has threatened to attack polling centres, election workers and security forces on Saturday, warning that voters will also get hurt.

More than 2,500 candidates are contesting 249 seats in the lower house of parliament, Wolesi Jirga. Among them are 406 women vying for 68 seats reserved for them under legislation designed to further their rights.

AFP