PESHAWAR: At least seven people were injured on Friday in grenade explosions after a public rally held by Pakistan's wildcard politician Imran Khan near the northwestern town of Swabi, police said.

“Unknown men threw two hand grenades on a police van and later opened fire after Khan's public meeting on the outskirts of Swabi, wounding seven people,” local police official Muhammad Shah said.

Shah said Khan had already left the venue when the attack happened, adding that the injured included four policemen.

Another local police official confirmed the incident.

More than 4,800 people have been killed across Pakistan in attacks blamed on the Taliban and other extremist networks based in the tribal belt since government troops stormed a radical mosque in Islamabad in 2007.

The 59-year-old former cricketer Khan has ridden a wave of support buoyed by mass rallies and has openly backed the courts' pursuit of embattled President Asif Ali Zardari and Prime Minister Yousuf Raza Gilani.

Speculation is widespread in Pakistan that Khan's party is being quietly groomed by the powerful military, which are believed to back moves in the courts to chip away at Zardari and Gilani's authority.