PUL-I-ALAM: Seven Pakistani workers kidnapped in Afghanistan were released on Monday after five days in captivity, police said.

The Pakistanis - engineers and workers on a hospital construction project in Logar province, just south of the capital Kabul - were freed unharmed, provincial police chief Ghulam Sakhi Roghliwani said.

It was not clear what prompted their release, he added, saying an investigation into the incident was underway.

The men were snatched at gunpoint Wednesday as they drove from their workplace back to their accommodation in Pul-i-Alam, provincial capital of Logar, which is troubled by the Taliban-led insurgency.

The police chief said he believed criminal gangs seeking a ransom payment were behind the abduction.

Abduction of rich Afghans and foreign nationals is relatively common in Afghanistan.

The Pakistanis were taken to an unknown location in Kabul after their release, the police commander added.