The hostages, ten women and two men, were released in three separate groups Wednesday, and handed over to the International Committee of the Red Cross, following an agreement reached in face-to face talks between South Korean and Taliban negotiators.
The source gave no details regarding time and place of the handover.
Under the agreement, South Korea has agreed to withdraw its troops from Afghanistan and impose a ban on its Christian missionary activities in the country.
The Taliban initially demanded the release of militants being held in prisons, but Afghan officials ruled out the possibility saying such a move was likely to create a dangerous precedent and encourage further abductions.
The Taliban abducted 23 South Koreans on July 19, hi-jacking their bus which was en route from Kabul to Kandahar on a humanitarian mission.
Militants earlier killed two male hostages and threatened to execute others, but after a round of negotiations with South Korea on August 12, the Taliban released two female hostages.
