The Taliban have stepped up their campaign of violence since the military launched a major offensive in mid-October in the militant stronghold of South Waziristan in Pakistan's lawless tribal area near the Afghan border. Friday's attack was the second in two weeks against a mosque used by Pakistan's security forces.
Most of the 10 people killed in the attack in the Lower Dir region were police leaving the mosque after Friday prayers, said the area's police chief, Feroze Khan.
The blast wounded another 28 people, also mostly police, said a local hospital official, Ghulam Mohammed.
Lower Dir is next to the Swat Valley, which Pakistani soldiers wrested from the Taliban earlier this year. But periodic attacks have continued in the area.
Militants have also staged attacks in Pakistan's heartland, many of them against the country's security forces.
A team of militants armed with guns, grenades and bombs raided a mosque near army headquarters outside of Islamabad on Dec. 4, killing 36 people.