An explosion damaged a girls' school in Khyber Pakhtunkhwa's Tank district on Wednesday, police said.

Officials said the explosive material had been fitted to a boundary wall of the under-construction middle school. As a result of the timed blast, the walls of the school were damaged while a classroom was completely destroyed, they added.

No lives were lost in the explosion, officials said.

They further said that a heavy contingent of police had surrounded the area and started a search operation to apprehend those responsible for the explosion.

Five to seven kilograms of explosive material were used in the blast, an official of the bomb disposal squad said.

The school was located 15 kilometres from Tank city, close to the South Waziristan tribal district.

In July this year, a grenade was hurled inside a school for Afghan children in Peshawar's Tajabad area. However, no one was hurt as no student was present there. No damage was caused to the building of Khushal High School either, a police official had said.

In the same month, an explosion took place at a girls' school in the Haider Khel area of North Waziristan tribal district when the students were taking their intermediate examination. No injuries were reported in the blast.

Last year, an explosion at a madressah in Peshawar killed eight students and injured around 120 others. A senior official had said at the time that the militant Islamic State group was the primary suspect in the bombing.