ISLAMABAD, Pakistan — Suspected Islamic militants fatally shot eight tribal leaders involved in efforts to broker a cease-fire between security forces and insurgents in Pakistan's volatile northwest, authorities said today.

The men were killed in separate attacks late Sunday and early today in South Waziristan, a mountainous region close to Afghanistan where al-Qaida and Taliban militants are known to operate, a security official and the military said in a statement.

The suspected insurgents killed three of the men in a market in Wana, the region's main town, while the other five were killed in attacks on their homes, the security official said. The men were scheduled to meet each other today in Wana to discuss the negotiations, the official said.

Pakistan is an ally in the U.S. war on terrorism, and its security forces have fought intense battles with militants in South Waziristan. Although the government has encouraged moderate tribal elders to broker a cease-fire in the region, there has been little sign of success.

The Pakistan-Afghanistan border area has long been considered a likely hiding place for al-Qaida leader Osama bin Laden and his top deputy Ayman al-Zawahri, and the U.S. has pressured the government of President Pervez Musharraf to crack down on militants operating in the area.

On Sunday, Pakistan reiterated that it will not let American forces hunt al-Qaida and Taliban militants on its soil, after a report in The New York Times said that the Bush administration was considering expanding U.S. military and intelligence operations into Pakistan's tribal regions.

The Pakistani government also has blamed Baitullah Mehsud, a South Waziristan-based militant leader with links to al-Qaida, in the Dec. 27 assassination of opposition leader Benazir Bhutto. Mehsud has reportedly denied involvement, and many Bhutto backers claim elements within the government played a role in her killing.