At least 10 people were injured on Tuesday in a blast at the election office of a Pakistan Tehreek-e-Insaf (PTI) candidate in North Waziristan, officials said.

“A huge explosion happened when I was inaugurating my election office in Razmak city,” Malik Aurangzeb Khan, PTI's candidate from NA-48 in the region bordering Afghanistan, told AFP.

“At least 10 people were injured in the blast,” he said, adding that he could not confirm the nature of the explosion.

A local administration official told AFP on condition of anonymity that an unidentified person threw a grenade at the gathering. A security source also confirmed the attack.

A large number of people suffered minor injuries in the grenade attack, while 10 people with major injuries were shifted to a nearby hospital, a source said.

There was no immediate claim by any militant groups for the blast.