Taliban fighters have released about 30 Afghan labourers who were among 150 people abducted nearly a week ago as they left an army base in the western city of Farah.

Nearly 120 workers had been released on Friday before the remaining men were handed over on saturday, according to Khalilullah Rahmani, Farah's provincial police chief.

Government officials and tribal elders had urged the Taliban to return the labourers after it emerged that the fighters thought they had captured soldiers when they stoppped three buses in a convoy on September 21.

"The Taliban had received a report that these people were going to join with the Afghan army, that they are receiving training in this camp that they are building," Abdul Qadir Daqeq, a provincial council member from Farah, said.

The Taliban took several days to question the labourers to determine that they were definitely not soldiers before releasing them, he said.

Their freedom was further delayed as they had been split up into six groups and held by six different factions.

Daqeq said that no ransom was paid and that the Taliban had not demanded the release of any of their fighters in exchange, as they have done in other kidnapping cases.

The labourers were working with an American construction company building for the Afghan National Army (ANA).

On Friday, Mohammed Naeem, one of the released labourers, said they had been treated well in captivity.

"Taliban abducted us thinking that we were ANA soldiers. They freed us after they realised that we are not soldiers," he said.

"Most of the people with us are carpenters, masons, painters and other construction workers."

Kidnappings have become increasingly common in Afghanistan with armed groups carrying them out for financial gain or in order to make political demands.