A bomb blast outside a mosque in Pakistan's tribal district of Bajaur on Sunday killed two anti-Taliban tribal elders and wounded two others, police and intelligence officials said.
The blast struck in Malangi village, about 30 kilometres (18 miles) northwest of Khar, the main town of Bajaur, which borders Afghanistan and was the focus of a recent operation against Islamist insurgents.
The attack came after four suicide bombers killed 36 people in a mosque in garrison city Rawalpindi on Friday, the latest in a wave of deadly blasts blamed on Taliban militants avenging military offensives against them.
"Two tribesmen were killed and two were injured in the blast. The bomb was planted outside a mosque," Fazal Rabbi, deputy chief of tribal police in Bajaur, told AFP by telephone.
An intelligence official in the area confirmed the incident and said that both the tribesmen were respected elders who spoke out against the Taliban.
Also on Sunday, Pakistani troops in northwest Swat district killed four militants including a local commander named Gul Mulla, the army said.
"An army convoy was attacked in the outskirts of Mingora. During the retaliatory fire four militants including Gul Mulla were killed," said Major Mushtaq Khan, a spokesman for Swat media centre.
On the outskirts of the northwest capital Peshawar, police killed one militant and arrested nine others in a raid on a religious seminary. Police said they recovered three suicide vests and arms from the madrassa.
Pakistan's military is currently engaged in offensives against Islamist militants across swathes of the northwest including the tribal areas, which have been branded the most dangerous place on earth by Washington.
The northwest has been plagued by instability for years, exacerbated in 2001 when a US-led invasion ousted the Taliban regime from Afghanistan, sending hundreds of Taliban and Al-Qaeda-linked militants into the lawless region.
About 30,000 troops backed by helicopter gunships and fighter jets poured into South Waziristan in October to try to dismantle Taliban strongholds.
But Washington and London are pressuring Pakistan to do more to capture Al-Qaeda leader Osama bin Laden and prevent militants crossing the border and targeting foreign troops stationed in Afghanistan.
Pakistani authorities, however, deny that bin Laden is on their soil, while Islamabad is focused on militants that are a domestic threat, with more than 2,600 people killed in Pakistan during a two-and-a-half year insurgency.