The incident took place in the Lakki Marwat district which is on the edge of a lawless tribal region divided on both sides of the border.

The improvised explosive device exploded near the military vehicle, killing seven soldiers including an officer, the army said in a statement.

“The perpetrators of this heinous act will be brought to justice,” it said.

There was no immediate claim of responsibility.

The tribal region has long been a safe haven for Islamist militants who operate on both sides of the border.

An umbrella group of Islamist and sectarian resistance groups called Tehreek-e-Taliban Pakistan (TTP) has been waging a war against the state to try to overthrow the government.

It wants to run Pakistan as an Islamic state governed by its own harsh interpretation of Islam.

Islamabad says the TTP leaders have taken refuge in neighbouring Afghanistan, where they run camps to train Islamist militants to launch attacks inside Pakistan.

Kabul has previously said rising violence in Pakistan is a domestic issue for Islamabad.

Relations between Pakistan and Afghanistan have soured in recent months. Islamabad says Kabul is not doing enough to tackle militant groups targeting Pakistan.