DERA ISMAIL KHAn - Militants blew up part of a newly constructed government school in South Waziristan Agency late Friday night, a spokesman for a wing of the Pakistani Taliban said on Saturday, the latest in a string of attacks on educational institutions. No one was hurt in the blast, but 18 labourers working on the site were abducted, said Azam Tariq, a spokesman for an arm of the Pakistani Taliban known as the "Sajna" group, which claimed responsibility for the attack. He said the workers were released a short time later.

"We have blown up the school because it was a government installation," said Tariq, warning the group would continue to attack government targets. Twenty people were killed and dozens wounded last month when militants launched an attack on Bacha Khan University in Khyber Pakhtunkhwa, a little more than a year after Taliban gunmen massacred 134 students at a military school in Peshawar.

The Peshawar school attack was seen as having hardened Pakistan's resolve to fight militants along its border with Afghanistan. Officials in South Waziristan said the girls' wing of the school in the Tehsil Tiarza area was damaged in Friday's blast, as well as some heavy machinery being used for ongoing construction at the site. The bomb destroyed three out of five classrooms of the primary school, a local security official told AFP.

Azam Tariq said the school had been targeted because it was run by the military and the group was opposed to female education.

Tariq told AFP that militants captured 18 people including school security guards and labourers before planting the explosive, but later released them.

Since 2002, when the army moved into northwestern tribal areas to fight the Taliban, militants have blown up hundreds of schools.

Overall, levels of militant-linked violence have dropped dramatically, with 2015 seeing the fewest deaths among civilians and security forces since 2007 - the year the Pakistani Taliban umbrella group was formed.

But the threat posed by the Taliban remains, particularly in the northwest.