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 Monday.

The tribal leaders were killed in separate attacks late Sunday and early Monday in South Waziristan, a mountainous region close to Afghanistan where Al Qaeda 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, a security official and an intelligence official said. The men were scheduled to meet each other Monday in Wana to discuss the negotiations, the officials said, speaking on condition of anonymity because they were not authorized to talk to media.

However, the military said in a statement that the eight tribesmen died in a single attack on the peace committee's offices in Shakai.

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.d

Also Monday, a homicide attacker driving a pickup truck detonated a bomb near a security post, wounding eight soldiers and two civilians, the military said in a statement.

The attacker died in the blast, which happened in Kabal in the Swat region, a former tourist destination where security forces have been battling loyalists of a pro-Taliban cleric. Swat is about 175 miles north of South Waziristan.

Elsewhere in South Waziristan, security forces exchanged gunfire with militants near the town of Ladha, but there was no information immediately on injuries, the intelligence official said. Fighting in Ladha last week following the kidnapping of four troops killed 25 fighters, the military said.

The Pakistan-Afghanistan border area has long been considered a likely hiding place for Al Qaeda 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 Qaeda 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 denied involvement, and Bhutto's supporters accuse the government of being involved in the attack.

About 2,000 supporters of the All Parties Democratic Movement, a coalition of small opposition parties that have called for a boycott of upcoming parliamentary elections, held a protest in Chaman near the Afghan border, chanting "Arrest the killers of Benazir Bhutto" and "Death to fraudulent elections."

Protesters also denounced the government for a scarcity of flour and electricity.

Rallies were scheduled for later Monday across the country, said Shahid Shamsi, a spokesman for Jamaat-e-Islami, Pakistan's largest Islamic group, which is also part of the anti-Musharraf coalition.