Qari Yousuf Ahmadi said the German was shot at 12:05 p.m. and that the other would be killed at 1 p.m. unless Germany announced a pullout. Ahmadi did not mention the at least 18 hostages from South Korea also held by the hard-line militia.

"The Germans haven't said they would pull out their troops from Afghanistan, that's why the Taliban's high commanders decided to kill the German," Ahmadi told The Associated Press by satellite phone from an unknown location. "Now we are giving them until 1 p.m. and if the German government won't pull out its troops, we will kill the other as well."

The two Germans and five of their Afghan colleagues were kidnapped on Thursday while working on a dam project in central Wardak province. A day later, militants kidnapped at least 18 South Korean Christians riding on a bus in Ghazni, one province to the south.

Ahmadi also warned the Afghan government and U.S. and NATO forces not to try to rescue the hostages, otherwise all would be killed. The provincial police chief in Ghazni province said his forces were working "carefully" to not trigger any retaliatory killings.

"The enemy has threatened that there shouldn't be any kind of search operation for the Korean citizens, otherwise we will kill them, that's why we are being very careful," said Ali Shah Ahmadzai. "We have surrounded the area but are working very carefully. We don't want them to be killed."

Ahmadi, who claims to speak for the Taliban, has said Seoul had until noon on Saturday to withdraw its 200 troops from Afghanistan, otherwise the South Korean hostages would be killed. Earlier on Saturday he said there had been no change in that demand.

The Korean troops in Afghanistan largely work on humanitarian projects such as medical assistance and reconstruction work. The troops run a hospital for Afghan civilians at the U.S. base at Bagram, and the facility has treated over 240,000 patients. The kidnapped civilians are not affiliated with the military.

"We are determined now to make more effort to give hope to the people," Korean Lt. Col. Kim Seoung Ki, 924th Korean hospital commander, said in a recent interview. "We will continue making contributions to bring peace in this land."

In South Korea, President Roh Moo-hyun vowed Saturday to make sincere efforts to win the release of the hostages, but did not detail what those efforts would be. He said 23 South Koreans had been abducted, but did not give an explanation for the discrepancy in the number of those kidnapped.

South Korea's Foreign Minister Song Min-soon reiterated Seoul's plans to withdraw troops from Afghanistan by the end of this year as scheduled, hoping to appease the militants.

"The government is in preparations to implement its plan" to pull its troops out of the war-ravaged country by the end of this year, he said.

The South Korean government informed parliament late last year that it would terminate its troop mission in Afghanistan and bring them home before the end of this year. South Korea has about 200 troops serving with the 8,000-strong U.S.-led coalition.

In the largest-scale abduction of foreigners since the fall of the Taliban regime in 2001, the South Koreans were kidnapped at gunpoint from a bus in Ghazni province's Qarabagh district on Thursday, as they traveled on the main highway from Kabul to the southern city of Kandahar.