Kabul - A bomb hidden in a motorbike was remotely detonated on Monday in western Afghanistan, killing two security guards and wounding seven others, police said.

The attack targeted Lal Mohammad Omarzai, district chief of Shindand district in Herat province, as he was entering the district headquarters compound Monday morning, western region police spokesman Abdul Raouf Ahmadi said.

"The bomb missed the district chief's vehicle but struck the second car, killing two bodyguards including Omarzai's son," Ahmadi said.

He said the wounded men, four of them in critical condition, were taken to hospital for treatment.

The Taliban claimed responsibility for the attack in a statement posted at their website and claimed that the attack killed five policemen including the district chief's son.

The insurgents have increased their roadside bombings and suicide attacks.

The provincial governor of southern Logar province and three bodyguards were killed in a roadside attack on Saturday in Paghman district, some 15 kilometres west of Kabul city.

Elsewhere, NATO forces killed one insurgent and wounded and arrested five others after the militants tried to attack an outpost in Ali Shing district of eastern Laghman province on Sunday, the alliance said in a statement.

"At about 1 am, two vehicles drove past the front gate of an outpost and fired automatic weapons," the statement said, adding the forces returned fire, disabling the vehicles, wounding five of the passengers and killing another.

Two of the attackers, who were carrying AK-47s, managed to flee from the scene, the statement added.

US-led coalition forces also detained eight suspected militants in multiple operations in Sabari and Qaladar districts of the south-eastern province of Khost on Sunday, the US military said in a statement.

The suspected militants were members of Haqqani network, an associated rebel group of Taliban involved in facilitating the movement of foreign militants in the region and attacks against the combined forces.

More than 4,000 people - mostly insurgents - have been killed in the Afghan conflict so far this year. (dpa)