Islamic militants holding two Chinese engineers hostage in Pakistan have threatened to kill one of them by 7 a.m. (Irish time) unless security forces end a siege of their hideout.
"There is a deadline of 12 o'clock (local time) but we have asked the tribe to ensure their safety," said a Pakistani security official.
"I am quite confident that the deadline will pass without any eventuality."
Earlier a correspondent for Arabic al-Jazeera television said a deadline of 6 a.m. had been set by the leader of the kidnappers, Abdullah Mehsud, who spoke to him about the group's demands in a telephone call.
Chinese diplomats have identified the engineers as Wang Ende and Wang Teng, who worked on Pakistan's Gomal Zam Dam project for China's state-run Sino Hydro Corp.
Pakistani officials said the engineers were kidnapped with one or two Pakistani security men early on Saturday.
The men were being held in South Waziristan, a tribal region bordering Afghanistan where security forces have been battling al Qaeda-linked militants since March.
Pakistani officials said the kidnappers, who had explosives strapped to their bodies, were with their captives in an isolated mud-brick house in the Chagmalai area of South Waziristan, surrounded by tribesmen and security forces.