DALIAN, Liaoning - An oil tank at a petrochemical plant caught fire on Monday morning in the coastal city of Dalian in Northeast China.

Plumes of thick black smoke towered over the plant and flames erupted out of the tank. It took about 300 firefighters and 50 fire engines three hours to finally put out the fire at 1:20 pm on Monday.

The tank was close to another three tanks storing diesel fuel, which was safely transferred to other places.

"It would have been disastrous if the fire spread to other tanks," said a retired worker from the plant surnamed Zhang, who lives nearby.

The oil tank began to burn at 10:06 am on Monday at the Dalian Petrochemical Company in Dalian city of Liaoning province. The company is a subsidiary of the China National Petroleum Corporation, the country's biggest oil producer.

About 800 tons of diesel oil were stored in the tank when the fire broke out, China National Petroleum Corporation said on Monday in a statement posted on its website.

No injuries were reported, and all the wastewater was recycled, local authorities said.

The environmental protection bureau in Dalian started to monitor the quality of air and nearby seawater after the accident, and no pollution had been reported as of Monday afternoon.

This is the second fire at the plant within two months at the company. On July 16, a refinery device caught fire at the plant but stopped short of causing any injuries. The fire was put out after about five and a half hours. Investigations have been launched into the cause of both accidents, local authorities said.

In July last year, an oil pipe blast at a port in Dalian also caused a massive oil spill in the sea.