At least 14 people, including two senior police officers, were killed and 85 others injured when a suicide bomber struck on Monday evening outside the Punjab Assembly in Lahore during a protest, police officials said.

Inspector General of Police (IG) Punjab Mushtaq Ahmad Sukhera said six police officials were among the dead, including two senior officers, while 85 people were also injured in the attack, which he said had targeted police officials present at the site.

The Jamat-ul-Ahrar faction of the banned Tehreek-e-Taliban Pakistan (TTP) claimed responsibility for the attack.

"The suicide attacker was on foot," Counter Terrorism Department (CTD) Chief Mohammad Iqbal told media.

Senior Superintendent of Police Operations Zahid Mehmood and Deputy Inspector General (Traffic) Lahore Capt (retd) Ahmad Mobin were among those killed in the attack.

Hours earlier, DIG Mobin had been seen on television, mediating with the protesters gathered at the site.

Mobin was reportedly at the site to negotiate with protesters for an end to the sit-in and to clear the area.

A large group of chemists and pharmaceutical manufacturers were gathered in front of the provincial assembly to protest a government crackdown against the sale of illegal drugs. There was a significant presence of law enforcers in the area while the protest was ongoing.

Rescue services, including ambulances and fire tenders, rushed the scene soon after the attack. An emergency was also declared in all hospitals of Lahore. Majority of the casualties were shifted to Mayo Hospital and Ganga Ram Hospital.

Prime Minister Nawaz Sharif condemned the attack and reiterated Pakistan was in decisive fight against terrorism. He lauded the sacrifices of the slain security personnel.

Army chief General Qamar Javed Bajwa instructed local military commanders and intelligence agencies to provide all necessary assistance to civilian authorities and arrest those responsible, a statement issued by the Inter-Services Public Relations (ISPR) read.

In a notification issued on February 7 to the Home Secretary, Punjab, the Provincial Police Officer and DG Pakistan Rangers Punjab, the National Counterterrorism Authority (NACTA) warned of a possible terrorist attack in Lahore.

NACTA directed that all vital installations, including important buildings, hospitals and schools, be kept under strict vigilance.

Last year, on Easter Sunday, at least 75 people were killed and over 340 injured in a suicide bombing that hit the main entrance of Gulshan-e-Iqbal Park, one of the largest parks in Lahore.

The attack targeted Christians who were celebrating Easter. Of the 75 dead, 14 were identified as Christians and the rest (61) as Muslims. The majority of victims were women and children.

Jamaat-ul-Ahrar, a group affiliated with the Tehree-e-Taliban, had claimed responsibility for the attack.

The attack led to worldwide condemnation and national mourning throughout Pakistan. In a result, Pakistan launched a widespread counter-terrorism operation in south Punjab, killing prominent leaders of banned outfits and arresting more than 200 people.