The kidnapping was the largest in the resurgent Taliban campaign against foreign forces since it was ousted from power by US-led troops in 2001.
The Taliban decided to free the hostages after Seoul agreed to pull all its nationals out of the central Asian country. They dropped their main demand that a group of prisoners held by the Afghan government be set free.
If a ransom was paid, some say it will make Afghanistan more dangerous for foreign nationals who already curb movement for fear of abduction either by the Taliban or bandits. Some embassies and aid organisations impose curfews on foreign staff.
"If it has happened, for sure it puts us in a difficult situation as it will encourage other kidnappers to take foreign hostages," said one Afghan government official, asking not to be named.
Seoul had already decided before the crisis to withdraw its 200 engineers and medical staff from Afghanistan by the end of 2008. Since the hostages were taken, it has banned its nationals from travelling there.
