Taleban militants in Afghanistan say they have extended a deadline for authorities to release 23 Taleban prisoners in exchange for 23 South Korean hostages.

A purported Taleban spokesman, Yousuf Ahmadi, told news agencies that government negotiators have until Monday evening (seven p.m. local time - 1430 UTC) for an exchange.

U.S. and Afghan forces have surrounded the town in Ghazni province where the hostages are being held. The Taleban has threatened to kill the hostages if troops attempt to free them by force.

In a standoff concerning a second set of hostages in Afghanistan, German Chancellor Angela Merkel said she would not give in to the demands of Taleban militants who seized two German engineers.

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

The two Germans were kidnapped Thursday in central Afghanistan. The Taleban claims it has killed both men and their five Afghan colleagues.

The body of one of the Germans has been recovered, but it is unclear what led to his death. Officials who have inspected the corpse say it has gunshot wounds.

The South Koreans, who officials said worked for an aid group, were kidnapped on a highway south of Kabul on Thursday.