A delegation of Pakistani tribal elders has met with the leader of al-Qaida-linked militants holding two Chinese engineers hostage, but failed to secure their release.

A member of the delegation says the militants' leader, who is at a different location, refused to order the hostages to be released unless the kidnappers and their captives are allowed to join him.

Abdullah Mehsud, who was freed in March from the U.S. prison at Guantanamo Bay, Cuba, ordered the abduction of the Chinese engineers, who have been held since Saturday in Pakistan's remote South Waziristan region.

He has threatened to kill the hostages if Pakistani security forces attack the kidnappers' besieged hideout.

The Chinese engineers were helping build a dam. Beijing has appealed to Islamabad to work for their release.