At least 19 people were killed and 12 others injured in an explosion at a chemical plant in Sichuan Province, in southwestern China, state news agency Xinhua reported on Friday.

The blast took place on Thursday afternoon in the city of Yibin and firefighters worked all night to extinguish the fire, said local authorities who are investigating the causes of the incident.

Images spread on social media show a dense column of smoke billowing over the factory belonging to Hengda Company, which mainly produces chemicals.

The 12 injured are in stable condition, according to the authorities.

Accidents are frequent in the Chinese industrial sector, where, despite new initiatives, regulations remain lax.

In 2015, the northern city of Tianjin was the scene of one of the most calamitous incidents in recent years in which a series of explosions at container storage depot at the Port of Tianjin killed 173 people and injured hundreds of others.