The blood-stained body of the bespectacled man was dumped in a field of clover beside a road in Arzoo, a village some 10 km (6 miles) from the eastern city of Ghazni.

"If the Kabul administration and Korean government do not give a positive reply to our demand about the release of Taliban prisoners by tomorrow 1200 (local time), then we will start killing other hostages," Taliban spokesman Qari Mohammad Yousuf told Reuters by telephone from an unknown location.

President Hamid Karzai's spokesman said bowing to Taliban demands would encourage more kidnapping.

"We shouldn't encourage kidnapping by actually accepting their demands ... In this situation we are doing what is the best for the interests of the hostages, and government," Humayun Hamidzada told reporters, without elaborating.

Karzai came under harsh criticism in March for releasing a group of Taliban prisoners in exchange for an Italian journalist.

"If we keep on responding positively to the demands of terrorists, we will face more problems," Hamidzada said.

Taliban spokesman Yousuf said Afghan negotiators had not contacted the Taliban since the second hostage was killed on Monday and said the insurgents suspected the Afghan government and foreign troops were planning a rescue bid.

Lives at risk 

Any attempt to rescue the hostages by force would put the Koreans' lives at risk, he warned.

The victim was identified as Shim Sung-min, 29, a former employee of an IT firm who did volunteer work to help the poor.

Police recovered his body from Arzoo, some 80 km (50 miles) from where the group of 18 women and five men were seized near Qarabagh on the main road south from Kabul. The distance between the two places undermines Afghan government claims to have the kidnappers surrounded.

The hostage crisis has focused attention on growing lawlessness in Afghanistan, where Taliban influence and attacks are spreading to areas previously considered safe, undermining support for a government unable to provide security.

Five Health Ministry officials, including three doctors, abducted by gunmen in southern Afghanistan on Sunday were freed unharmed on Tuesday, a provincial police chief said.

Shim's mother cried hysterically after hearing the victim may have been her son. "Why did you kill him? Please save his life," she said through her tears.

Seoul called the killings a "heinous act" carried out on innocent Korean civilians whose government had no power to release Taliban prisoners from Afghan jails.

South Korea "makes it clear it will not tolerate any further acts of harming innocent Koreans and holds the perpetrators responsible," a Korean presidential statement said.

The Taliban shot Shim after the expiry of other deadlines they had set for the release of rebel prisoners.

Talks deadlocked 

Negotiations were deadlocked on Tuesday with Afghan authorities demanding the release of the 18 women before any prisoners were freed and the kidnappers insisting its fighters should be let out of jail first, a Western security analyst said.

Taliban spokesman Yousuf said Shim had been killed because Afghan authorities were ignoring their demands.

On Wednesday, the Taliban killed the leader of the group.

Al Jazeera television broadcast a video showing at least seven of the female hostages, wearing headscarves and apparently unharmed. Four were sitting on the ground, the rest standing beside men in Afghan clothes, apparently militants.

The seizure of the Koreans came a day after the Taliban had seized two Germans and five Afghans in nearby Wardak province.

The body of one of the Germans was found with bullet wounds, but the other German and four Afghans were still being held by the Taliban who want Germany to pull troops out of Afghanistan. One of the Afghan captives managed to escape.

Source: Reuters