The threat came less than 24 hours after the bullet-riddled body of a 29-year-old male church volunteer was found beside a road in the Andar district in central Afghanistan.

Taliban rebels abducted 23 South Koreans -- 17 of them women -- from a bus on July 23. Last Wednesday, the group's leader was executed, al-Jazeera said.

Taliban spokesman Qari Yousef Ahmadi said senior leaders decided to kill the male captive Monday night because the government hadn't met demands to trade eight prisoners for the Christian group, The New York Times said.

The latest execution angered regional Gov. Mejaruddin Patan, who issued a statement saying: "Today the Taliban proved to the world that they are criminals. Even while our negotiations were continuing they killed another hostage."