Hundreds of tribesmen gathered Tuesday near the area where suspected Al Qaeda-linked militants are holding two Chinese engineers and demanding safe passage to Abdullah Mehsud (search), their reputed leader and a former U.S. prisoner from Guantanamo Bay, Cuba, officials and residents said.

The tribesmen are trying to pressure the five militants into releasing their captives, held since Saturday.

Officials say the militants have strapped explosives to themselves and the Chinese and are threatening to kill the captives unless they are allowed safe passage to t some six miles away.

The Chinese, who work on a dam project in the lawless South Waziristan (search) region near the Afghan border, were kidnapped along with their Pakistani driver and security guard, and are being held in a mountain mud-brick house near the village of Chagmalai. Beijing has appealed to Pakistan to work for their release.

The kidnappers initially told the government through local sympathizers that they were ready to trade the hostages for foreign militants captured by the army during a recent military operation against Al Qaeda fighters in South Waziristan.

On Tuesday, a group of influential elders from the Mehsud tribe gathered in the town of Barwand, seeking talks with Mehsud, and if possible, the kidnappers — believed to include at least two foreigners. Hundreds more tribesmen were arriving to put additional pressure on Mehsud, fearing that the whole tribe could be liable for punishment if the engineers are killed.

Information Minister Sheikh Rashid Ahmed, in the northwestern city of Peshawar, said he hoped efforts by the tribesmen would be successful in releasing the Chinese.

He added that authorities have chosen not to use force against the kidnappers because of fears for the safety of the two Chinese.

Officials say Mehsud is a local man but used to fight with the Taliban and was a former U.S. prisoner at Guantanamo Bay (search). He is thought to be hiding with foreign and local militant supporters in Barwand area.

"We are upset on the kidnapping of the Chinese who were building a dam to give us water and electricity," said Inayat Mahsud, the head of a tribal council, before leaving for an undisclosed location for talks with Mehsud.

China is a longtime ally of Pakistan. The engineers were among between 70 and 80 Chinese who are working for a Chinese state-owned company at the Gomal Zam dam, about 210 miles southwest of the capital, Islamabad.

"The kidnappers, who include foreigners, want to take the Chinese to another area. They are seeking safe passage but we will not accept this demand," Brig. Mahmood Shah, chief of security for Pakistan's northern tribal regions, told The Associated Press in a telephone interview.

Shah also has said they are prepared to let the kidnappers leave the area without the hostages.

South Waziristan has been the scene of a series of military operations against hundreds of suspected foreign militants — Central Asians, Arabs and Afghans among them — and their local supporters in recent months. Scores of militants were killed or captured.