Gunmen on Thursday, July 12, shot dead nine Pakistani police prison staff as they slept in Lahore, the second attack on security forces in the country's political heartland since Islamabad reopened a NATO supply corridor, AFP reports.

The Pakistani Taliban claimed responsibility for the dawn raid, in which police said 10 gunmen stormed a hostel housing officers being trained from the troubled northwest.

The killings, and a similar assault on an army camp on Monday, raise fears of a fresh wave of violence in Punjab, the country's most populous province that will be vital in upcoming elections, and which for the past year had seen a lull in Taliban attacks.

Punjab police chief Habibur Rehman said the attackers came on three motorcycles and one car, armed with Kalashnikov rifles and hand grenades.

They then stormed the building in the densely populated area of Ichra, where around 30 police prison staff were sleeping early in the morning.