Kabul's chief criminal investigator has been wounded and two of his guards killed in a bomb blast at a police post where they were investigating an attack on three of their colleagues.

General Alishah Paktiawal, who was only lightly wounded, was the apparent target of the blast, according to the interior ministry.

Paktiawal is a high-profile police official who often attends the scenes of bombings and who personally leads raids on the city's numerous criminal gangs.

He is protected by a large security detail and has survived several attempts on his life.

Zemeri Bashary, an interior ministry spokesman, said that Paktiawal and his guards had gone to the police post to investigate an overnight attack by "armed men".

Bomb attack

"Paktiawal and his men had gone there to investigate an attack on the post last night. As they entered the post, a bomb exploded which killed two officers and slightly injured Paktiawal," Bashary said.

Armed men had stormed the police post late on Tuesday and shot dead the three policemen inside, Bashary said.

He did not say who might have been responsible for the attack.

The Reuters news agency reported a police official as saying the blast was caused by a landmine.

Kabul, which is patrolled by hundreds of Afghan and international security forces, has nonetheless seen several attacks and suicide bombings.