SHIJIAZHUANG - Over 100 fishermen on Tuesday filed a lawsuit against US energy giant ConocoPhilips's China branch, as they believe the company is responsible for June's massive oil spill in north China's Bohai Bay, according to their lawyer.

They filed the lawsuit in a maritime court in the northern port city of Tianjin, asking ConocoPhilips China to pay 490 million yuan ($77.78 million) to 107 fishermen from Hebei province.

The fishermen claimed that the oil spill killed many of their clams and sea cucumbers, said Zhao Jingwei, a lawyer with the Beijing-based Yingke Law Firm.

The fishermen must wait seven days for the court to decide if it will accept the case.

The oil spill has polluted over 6,200 square km of water in the bay since June, an area about nine times the size of Singapore.

The State Oceanic Administration (SOA) said last month that its investigation revealed that operations in the bay's Penglai 19-3 oil field were in violation of the region's development plan. The SOA also found shortcomings in ConocoPhilips China's management system.

The SOA said the company "failed to take necessary preventive measures after signs of a problem emerged."

ConocoPhilips China operates the Penglai 19-3 oil field with its Chinese state-owned partner, the China National Offshore Oil Corporation.