Taleban militants Monday again extended a deadline to negotiate the release of 23 South Korean aid volunteers held by militants in Afghanistan.

The new deadline gives South Korean and Afghan officials an additional 24 hours until 1430 UTC Tuesday, or 7 pm local time to reach an agreement with the Taleban.

The militants are demanding freedom for 23 Taleban prisoners in exchange for the South Koreans. The Taleban has threatened to kill the hostages if the demands are not met.

Militants had already extended the deadline until Monday. As the set time approached, Taleban told news agencies that negotiations were not going well.

An Afghan Interior Ministry spokesman Zemarai Bashary said Monday the government is working around the clock to secure the release of the Koreans, as well as one German captive.

A Taleban spokesman Monday said the German hostage, as well as four Afghan hostages, are still alive. The Taleban had earlier said they had been killed.

The body of a second German kidnap victim was recovered on Sunday.

The Koreans were abducted Thursday on a bus between Kabul and Kandahar. They were in Afghanistan to do volunteer humanitarian work.

U.S. and Afghan forces surrounded the town in Ghazni province where the South Koreans were held.

German Chancellor Angela Merkel has said she will not give in to the demands of Taleban militants who seized the German engineers.

The kidnappers have demanded Germany's 3,000 troops withdraw from Afghanistan. Ms. Merkel said Germany will not give in to blackmail.

In Seoul, South Korean officials are warning citizens that unauthorized travel to Afghanistan will be punishable by prison time and fines.

Some information for this report was provided by AFP and Reuters.