The six enlisted men and one officer were killed by an "improvised explosive device" in Lakki Marwat district of Khyber Pakhtunkhwa province, the military said in a statement.

A senior police officer stationed in Lakki Marwat told AFP that "the explosion completely destroyed the vehicle".

"We have received information that the vehicle came under fire after the blast," he added, speaking on condition of anonymity.

Mountainous Khyber Pakhtunkhwa has long been a hive of Islamic militant groups including the Pakistani Taliban and the local chapter of the Islamic State group.

"Lakki Marwat is one of the districts in Khyber Pakhtunkhwa most affected by terrorism," the senior police officer told AFP.

No group immediately claimed responsibility for Sunday's attack.

The Pakistani Taliban -- known as Tehreek-e-Taliban Pakistan (TTP) -- is the most active militant group in the area and regularly targets security forces.

Attacks have spiked in Pakistan since the Taliban returned to power in neighbouring Afghanistan in August 2021.

Last year, 29 suicide attacks were registered -- the most since 2014 -- killing 329 people, according to the Pakistan Institute for Conflict and Security Studies.

Islamabad accuses Kabul's new rulers of failing to root out militants sheltering on Afghan soil as they prepare to stage attacks on Pakistan.

The Taliban government has repeatedly denied the allegations, and said it will not allow Afghan territory to host foreign militants.

However analysts say the TTP share a common lineage and ideology with the Afghan Taliban.

In January 2023, the TTP was linked to a mosque suicide bombing in the Khyber Pakhtunkhwa provincial capital of Peshawar which killed more than 80 police officers.

In September, Pakistan said four troops were killed during a cross-border raid by "hundreds" of TTP fighters in Chitral, an area popular with domestic tourists.