The captors of two Chinese engineers threatened to kill their hostages on Monday unless Pakistani authorities released up to six of their accomplices, Pakistani Interior Minister Aftab Ahmad Khan Sherpao said.

In an interview with the BBC, the minister said the kidnappers were under the control of Pakistani tribal leader Abdullah Mehsud, a former Taliban commander and chief of the militants in Pakistan's South Waziristan tribal area. Mehsud, who is not in the same location as the hostages and their captors, claimed responsibility on Sunday for the abduction.

Sherpao said four militants were involved in the kidnapping, one Afghan, one Uzbek and two others who are probably of Pakistani origin. Earlier reports said there were five kidnappers.

Sherpao said the kidnappers, through their messenger, are demanding the release of a number of their accomplices, although the precise number and identities remain unclear.

Mehsud reportedly threatened to kill one of the hostages unless security forces allowed the captors and hostages to join him. However, he allowed his deadline to pass because negotiations were under way, according to AFP.

Mehsud has been described by intelligence agencies as an Al Qaeda "facilitator."

Sherpao said that Pakistani security agents know where the hostages are being held. The militants have strapped explosives to their bodies and, according to AP, to those of the hostages as well.

Tribal sources said the kidnappers have also demanded an end to military operations in South Waziristan, a remote tribal area where hundreds have died in battles between Pakistani security forces and Al Qaida-linked militants since March.

A tribal council meeting was held Monday to negotiate with the kidnappers for a peaceful resolution to the standoff but there were no conclusive results, said Pakistan's local English-language newspaper Dawn.

Negotiations for the hostages' release continue and the Chinese embassy in Islamabad is closely following events.

"We thank the Pakistani government for their all-out effort to rescue the hostages and believe that they will resolve the issue," said Zhang Yiming, a spokesperson for the Chinese Embassy in Islamabad.

The two engineers, Wang Ende and Wang Peng, were kidnapped Saturday by gunmen near Jandala. The area lies on Pakistan-Afghanistan border.

The hostages are reported to be in good condition at present.

The engineers have been working on a dam and a canal in the region for the China National Water Resources and Hydropower Engineering Group Corporation.

(Xinhua News Agency, China Daily October 12, 2004)