The attack was the latest in a nationwide wave of violence blamed on Islamic militants that has left more than 200 people dead since the army stormed the radical Red Mosque in the capital Islamabad earlier this month.

The troops’ vehicle had just entered the rugged South Waziristan tribal zone “and was distributing rations at a checkpost when it hit an improvised explosive device,” local police official Mumtaz Zareen told AFP.

Security officials said two soldiers were seriously injured and four others suffered minor wounds in the blast near the town of Tank.

Earlier troops traded gunfire with pro-Taleban militants in the neighbouring region of North Waziristan after rebels launched rockets at government and army buildings, officials said.

There were no immediate reports of casualties.

One rocket damaged a government-run student hostel in Miranshah, the main town in North Waziristan, while two landed on the lawns of the main military base in the town, local security officials said.

Troops responded by targeting suspected insurgent positions in the surrounding mountains with light and heavy weapons in an exchange of fire that lasted for around three hours, they said.

Army helicopter gunships also flew over the area and the sound of frequent shelling was heard, residents said.

Seven people, including three soldiers, were killed in North Waziristan on Monday.

The tribal areas have seen a spike in violence since militants in North Waziristan scrapped a peace deal with the government on July 15, five days after the army stormed the Red Mosque in the capital, leaving scores dead.

The United States, Islamabad’s key ally, has branded Pakistan’s tribal belt a safe haven for Osama bin Laden’s Al Qaeda movement, a charge that Pakistani officials deny.