Fears for the hostages rose after police recovered the body of a German engineer. The Taliban earlier said it had killed two Germans seized separately from the Koreans, but Kabul and Berlin insisted one of them was still alive.

A special team from Seoul flew into the Afghan capital for talks with officials, ahead of a 1430 GMT deadline set by the Islamic rebels to kill the South Koreans unless the same number of jailed Taliban fighters are freed.

The double hostage crisis is the latest in a series of abductions targeting the 37 countries with forces in Afghanistan. The Taliban have demanded that the 3,000 German troops and 200 South Korean soldiers be sent home.

Seoul reaffirmed that it would withdraw its troops from Afghanistan by year's end as planned as it scrambled to free the group of evangelical Christian Koreans, about 18 of whom are women aged mostly in their 20s and 30s.

The Afghan defence ministry said its forces backed by the US-led coalition had taken up positions in the Qara Bagh district of southern Ghazni province where the Koreans were being "held in the hands of enemies of the people."

The soldiers "are awaiting attack orders on suspected areas. Whenever the authorities consider it appropriate they'll launch the offensive," the ministry said in a statement.

The 14,000-strong coalition however said it had not yet been asked to help, although it added that it would support any rescue operation in the insurgency-hit region if requested.

"There has not been any fighting or engagement yet," defence ministry spokesman General Mohammad Zahir Azimi said.

The Korean Christians were seized on Thursday while travelling on a bus along the highway linking southern Kandahar -- the birthplace of the Taliban -- and Kabul during an aid mission in the war-torn country.

The Germans were kidnapped the previous day along with five Afghans, and a Taliban spokesman on Sunday reaffirmed claims that the rebels had killed all of them after Berlin and Kabul failed to meet tight deadlines for talks.

"We have recovered the body of one German," said Hewas Mohammad Muslim, the police chief of the southern province of Wardak, without specifying the cause of death. "That is all I know at this point."