There is no word on the fate of the remaining 21 South Korean hostages held by the Taleban in Afghanistan, after the militants' latest deadline passed Wednesday.
The Taleban had given the government until noon local time, 0730 UTC, to meet their demand of exchanging prisoners for the hostages.
The Afghan government has refused to free jailed militants. Two of the hostages have already been killed and a self-described Taleban spokesman Qari Yusuf Ahmadi said more hostages will die if the group's demand is not met.
In Seoul, relatives of the hostages made an emotional appeal to the U.S. Embassy officials for help in negotiations.
Earlier, U.S. State department spokesman Tom Casey said there is regular contact between U.S. and South Korean officials on the crisis, but he did not elaborate.
Separately, a top official in Ghazni said the Taleban have killed four Afghan court officials they kidnapped two weeks ago. The official said those bodies were discovered south of Ghazni town Wednesday.
Twenty-three South Korean Christian volunteers were abducted on July 19 while traveling by bus to southern Kandahar province, a Taleban stronghold. The bodies of two of them (identified as Shim Sung-min and Bae Hyung-ku) have been found in neighboring Ghazni province.
Tuesday, U.S.-based Human Rights Watch urged the Taleban to immediately release all hostages in its custody, saying their abduction amounted to war crimes.
Also on Tuesday, the Arabic television network Al-Jazeera aired a video of a German hostage held separately by the Taleban. In the tape, the hostage pleaded for his life at gunpoint and urged the United States and Germany to withdraw their troops from Afghanistan.
Some information for this report provided by AP and Reuters.