DALIAN, Aug. 18 -- The fire that broke out Thursday in a chemical plant in Dalian, northeast China's Liaoning Province, was caused by leak in an oil pump, authorities said Friday.

The fire broke out at around 6:40 p.m. in a subsidiary of state-owned PetroChina Company Limited in the coastal city, according to the local publicity department. No casualties were reported.

Liu Yan, Dalian's deputy mayor, said that the leak occurred in a pump in the company's catalytic cracking unit that churns out 1.4 million tonnes of heavy oil annually.

Representatives from the company said that the accident showed vulnerabilities in safety management.

"We need to learn lessons from the fire and launch a safety inspection to rule out further risks," Liu said.