Afghan military officials say national and foreign forces have launched a major operation to free 23 South Korean hostages taken by Taleban militants earlier this week. A Taleban spokesman says the group will begin to kill the Koreans Sunday evening unless the insurgents' demands are met. Correspondent Benjamin Sand reports from VOA's South Asia bureau in Islamabad.

Afghan officials say troops have moved into several areas in eastern Afghanistan where the Korean hostages may be located, but so far no fighting has been reported.

As the joint operation began Sunday morning, a high-level South Korean delegation reached Kabul, hoping to help facilitate the hostages' release.

Taleban militants seized the group of the evangelical Christian Koreans on Thursday southwest of Kabul, and have threatened to kill them unless South Korea withdraws its troops from Afghanistan and the Afghan government frees a number of Taleban prisoners.

Korean officials describe the group of eight men and 15 women as "medical and humanitarian volunteers." South Korean president Roh Moo-hyun issued a televised appeal for their safe return on Friday, and insisted Seoul would conduct "sincere" negotiations for their release.

On Sunday, supporters and family members held vigils in the South Korean capital, pleading for a swift resolution of the crisis.

Surrounded by reporters, this young man says that if anything happens to the hostages, he will have nothing left to live for.

South Korea only has around 200 non-combat troops in Afghanistan, and they were already scheduled to leave the country by the end of the year. The South Korean Defense Ministry says preparations for their withdrawal have already begun.

In Afghanistan, local tribal leaders are reportedly helping direct talks with the purported Taleban captors in Ghazni, southwest of Kabul. A man calling himself a Taleban spokesman said any attempt to forcibly free the hostages would result in bloodshed.

On Saturday, Taleban forces claimed they had executed two German hostages they had captured three days earlier.

Afghan officials recovered the body of one of the Germans Sunday, but are disputing the Taleban's claims.

Both German and Afghan authorities say the man died of natural causes induced by the stress of his captivity.

Officials say they believe the second hostage is still alive.