BEIJING - Petrochemical projects near North China's Bohai Bay have been a boon to the local economy but pose a threat to the region's environment, experts warn.

Many large refinery and petrochemical projects have been established on land near the bay, putting serious pressure on its environment. Pollution from those operations threatens to turn the waters there into a "dead sea", especially since it is difficult to purify an inland sea, the Shanghai-based Oriental Morning Post reported on Tuesday.

Liaoning province, which borders Bohai Bay, contains at least six large refineries that can process millions of tons of crude oil every year. In two other nearby places - Shandong province and Tianjin - oil refineries and petrochemical businesses also give a considerable boost to the local economies, according to the paper.

Qiu Shengyao, an oceanic expert at Yantai University in Shandong province, said Bohai Bay offers the oil industry more advantages than many other bodies of water in China.

He said the inland sea contains a large number of oil and gas fields, and its shallow depth makes it an easier place to draw those resources from than many spots in the ocean.

In addition, the land surrounding the bay contains many factories and industries, which often use large amounts of oil.

Qiu called on the industry to do more to protect the environment.

"That's not to say that people should drop the whole business," Qiu said. "But companies have to take measures to protect the local environment and protect the sea from natural or man-made disasters."

A series of accidents caused by petrochemical businesses have given rise to public fears.

In Dalian, an oil tank at a China National Petroleum Corp plant caught fire on Monday, the second blaze to occur at the plant within two months.

The previous year saw a pipeline at the plant explode and a fire start at a site where oil was being stored. Some of the blame for the recent leaks has fallen on oil-exploration companies. In the Bohai Bay case, ConocoPhillips has been criticized for what some see as its reluctance to clean up oil leaked from the Penglai oil field into the bay, which the company helps to operate.

"The series of accidents suggests these enterprises have a tendency to cause environmental disasters," said Bao Jingling, chief engineer of the Tianjin bureau of environmental protection. He said it is important to encourage companies to establish systems that can warn the public of potential environmental hazards and to form contingency plans for dealing with large releases of pollutants.

Qiu said the concentration of petrochemical projects in the bay also makes the industry particularly vulnerable to natural disasters.

"The Bohai Sea is threatened by storm tides, earthquakes and sea ice," Qiu said. "All of those things could endanger oil-drilling and refining operations."

Qiu said new petrochemical projects in the region should be built according to environmental regulations and that government officials should monitor existing plants to make sure they fulfill their responsibility to protect the environment.