BEIJING (Reuters) - A fire that broke out on Thursday at state oil major PetroChina’s plant in northeastern China, one of the country’s largest refineries, has been put out with no reported casualties, state media reported.

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The fire came just two months after the Dalian refinery finished a planned major maintenance.

More than 600 firefighters extinguished the blaze at the plant’s 1.4 million-tonnes-per-annum catalytic cracker just after 9:00 p.m. (1300 GMT), and stayed on the scene to make sure equipment at the refinery remained cool, state broadcaster CCTV said on Friday.

The inferno, the latest industrial incident to rock the port city of Dalian, started at around 6:40 p.m. due to a broken seal in a feed pump, CCTV said.

The refinery in Liaoning province and owned by PetroChina Dalian Petrochemical Corp, has three crude distillation units with total processing capacity of 410,000 barrels per day of crude oil. Catalytic crackers typically produce gasoline.

A spokesperson for PetroChina said the feedstock equipment connected to the catalytic cracker has been suspended. The other units in the refinery were not affected.

The unit that caught fire produces all oil products but is geared towards gasoline, according to a Singapore based trader.

Firefighters battled huge flames and billowing smoke, pictures on the People’s Daily twitter account showed.

Local government officials were at the site on Thursday evening as an investigation began into the cause of the inferno, state radio reported on its social media blog.

Environmental inspectors are carrying out checks but said containment pools installed at the refinery had prevented pollutants from entering coastal waters. Nearby air quality monitoring stations showed no signs of abnormal emissions in the area, CCTV reported.

The plant’s crude processing operations were not affected, although there may be a small reduction in output at the gas separation unit as a result of the incident, a refinery source said.

In 2013, an explosion at the refinery left two people injured and two missing. [bit.ly/2v4vloW]

Dalian was also the site of one of China's biggest known oil spills, when a pipeline blast put at least hundreds of thousands of gallons of oil into the sea in July 2010. [bit.ly/2uTYTGq]