Unknown attackers lobbed a hand grenade on a mobile police vehicle in Pakistan's Nasirabad district on Friday.

Officials told Dawn News a police party was on patrol in the area when the armed men raiding motorcycles hurled a grenade which exploded near the police vehicle that was badly damaged.

The police personnel, who were travelling in the vehicle, remained unhurt.

Police and other law enforcement forces launched a search operation to trace the attackers.

No arrests have been made so far.