An explosion near the Punjab provincial assembly in the Pakistani city of Lahore has killed at least 13 people and injured 83 others, a senior police official said.
- Taliban faction Jamaat-ur-Ahrar has claimed responsibility
- Officials say negotiations were underway when the perpetrator detonated the bomb
- Jamaat-ur-Ahrar pledges a new wave of attacks on government departments
Mushtaq Sukhera, inspector general of police in Punjab province, said five police officers were among the dead when an explosion rocked a protest organised by Pakistan's chemists and pharmaceuticals manufacturers.
"It was a suicide attack. The bomber exploded himself when successful negotiations were underway between police officials and the protesters," Mr Sukhera said.
A spokesman for Jamaat-ur-Ahrar, a faction of the Pakistani Taliban, has claimed responsibility.
The militant group also warned the Lahore attack was the start of a new campaign against government departments.
"You are on our target across the country," it added in a statement.
Jamaat-ur-Ahrar had also claimed responsibility for an Easter Day bombing in Lahore last year that killed more than 70 people in a public park.
Security in Pakistan has vastly improved in recent years but Islamist groups such as the Pakistani Taliban and Islamic State still pose a threat and have carried out mass attacks.
Prime Minister Nawaz Sharif said the attacks would not weaken Pakistan's resolve in the fight against militancy.
"We have fought this fight against the terrorists among us, and will continue to fight it until we liberate our people of this cancer, and avenge those who have laid down their lives for us," he said in a statement.