Police in Pakistan say a suicide attacker has detonated a large bomb at a protest rally in the city of Lahore, killing at least 11 people and injuring 60.

The blast struck outside the Punjab Assembly, with police officers and journalists covering the march among the casualties.

The attacker, a member of a group allied to the Pakistani Taliban, drove a motorbike into crowds before detonating an explosive device.

Vehicles on Lahore’s Mall Road, a major thoroughfare that passers through the centre of the city, were also destroyed in the bombing.

Rescuers were at the scene and the area has been cordoned off.

The protest was organised by pharmacists in Punjab unhappy about new drug rules enforced by the regional government.

Police said two senior members of Lahore's security force were among the dead.

A group called Jamaat-ul-Ahrar claimed the attack in a text message, saying it was revenge for Pakistani military operations against Islamic militants in tribal regions along the Afghan border.

"We just couldn't understand what happened," Tufail Nabi told Geo News TV.

"It was as if some big building collapsed.”

Lahore is the capital of Punjab province and was targeted on Easter Sunday last year in an attack that claimed the lives of 75 people.

People cry during the funeral of their loved ones a day after a suicide bomb attack at a park, in Lahore, Pakistan, in 2016 (EPA)

That suicide bombing targeted Christians although the majority of the dead were Muslim.

A group affiliated with the Pakistani Taliban claimed responsibility for the attack.