A suicide bomber targeted a mosque in Mohmand Agency's Anbar tehsil, leaving at least 24 people dead, including five children, and 31 others injured.
The injured were transported to hospitals in Bajaur Agency, Charsadda and Peshawar for treatment.
The bombing took place in the village of Butmaina in the Mohmand tribal district bordering Afghanistan, where the army has been fighting against Taliban militants.
Akbar said that the bomber came in as Friday prayers were in progress and blew himself up in the main hall. A curfew was later imposed in the area.
Pakistan's tribal regions, which border Afghanistan, were considered to be strongholds of Pakistani Taliban militants until 2014 when the military launched a major operation there, evicting and killing large numbers of insurgents. However, violence has continued in some of the tribal regions.
Friday's attack came hours after army chief Gen. Raheel Sharif met with Prime Minister Nawaz Sharif to discuss security issues. According to a government statement, Sharif pledged to continue the war against terrorism.
The military says some 18,000 civilians and 5,000 soldiers have been killed in militant attacks in Pakistan since the September 11, 2001 attacks in the United States, when Islamabad threw its support behind Washington in the war on terror.
(The article has been updated on Saturday, Sept 17)