Taliban fighters would kill 23 South Korean hostages if Afghan authorities fail to release 23 Taliban prisoners before 7:00 p.m. (1430 GMT) on Sunday, a purported Taliban spokesman Yousuf Ahmadi said on Saturday.

Ahmadi said from an undisclosed place by telephone that the hostages would be executed once the deadline expires, but he did not mention the identities of the prisoners demanded to be freed.

The 23 South Koreans were kidnapped by Taliban militants on a road in the central Ghazni province on Thursday afternoon.

Ahmadi, who said on Friday that only 18 South Korean nationals were abducted, said that some hostages spoke so fluent Afghan language that Taliban fighters had regarded them as Afghans.

The Taliban also demanded the withdrawal of 200 South Korean troops from Afghanistan. The South Korean government said the soldiers would be pulled out at the end of 2007 as scheduled.

Meanwhile, two Germans were abducted together with five Afghans in the central Wardak province on Wednesday.

Ahmadi claimed all seven hostages were executed on Saturday afternoon as both the German and Afghan governments did not meet the Taliban's demands for the withdrawal of German troops from Afghanistan and the release of some Taliban prisoners.

However, Afghan Foreign Ministry spokesman Sultan Ahmad Baheen told Xinhua that one German hostage was still alive and the other had died of a heart attack.

Taliban militants have carried out kidnappings in Afghanistan over the past two years frequently, and killed some hostages.