Afghanistan's Taleban says the group will begin killing some of its 22 South Korean hostages unless the government agrees to release Taleban prisoners by noon (local time) Monday.
A Taleban spokesman said Sunday that negotiations between the militant group and the Afghan administration are deadlocked.
The Taleban says it wants at least eight prisoners freed in exchange for the hostages.
The Afghan government says a team of lawmakers and tribal elders is trying to persuade the Taleban to free the kidnap victims without conditions.
Afghan President Hamid Karzai met with a South Korean presidential envoy earlier Sunday to discuss the hostage situation.
In his first comments about the case, Mr. Karzai condemned the kidnapping as being "un-Islamic" and against Afghan culture.
The South Korean Christian aid workers - most of them women - were abducted 10 days ago (July 19th) in southeastern Afghanistan.
The kidnappers killed the leader of the volunteers last week.
Some information for this report was provided by AFP, AP and Reuters.