The five construction workers were killed when a bomb exploded underneath their vehicle in Paktika province, local police chief Sardar Mohammad Zazi said, adding that the device was detonated by remote control.

Two others were wounded in the attack, which the police chief blamed on fighters with links to the Taliban, which has waged a violent insurgency in Afghanistan since being toppled from power in a US-led invasion in late 2001.

Also in Paktika, an Afghan man was killed and three people hurt when a rocket fired from Pakistani territory at a Nato base landed instead on a group of homes in Barmal district, said provincial governor Mohammad Akran Ikhpolwak.

To the north in neighbouring Paktia province, unknown assailants opened fire on the chief of Showak district late Saturday, gunning down two of his bodyguards, deputy provincial police chief Ghulam Dastgir told AFP.

In volatile southern Helmand province, where insurgent attacks occur almost daily, three "very important" Taliban figures were killed on Saturday in clashes with security forces, the defence ministry said in a statement.

And a suspected suicide bomber died late Saturday in eastern Khost province when the explosives he was carrying apparently blew up prematurely, a local spokesman said.

More than 50,000 Western troops, the bulk of them under a Nato-led International Security Assistance Force, are deployed in Afghanistan.