Oil leaks continue at two platforms operated by ConocoPhillips in Bohai Bay, more than two weeks after authorities ordered them to shut down, China's ocean watchdog said on Friday.

The State Oceanic Administration has ordered the company to stop the leaks, contain the oil spills, clean up polluted areas and conduct a thorough investigation to eliminate the possibility of further oil spills before Aug 31.

Several oil belts were detected by the administration on July 27 in a 4.6-square-kilometer area to the east of the Penglai 19-3 oilfield, and the administration's surveillance has determined that Platform C is still leaking about 2.52 liters of oil a day and that there are more oil slicks near Platform B.

ConocoPhillips reportedly admitted that "small and intermittent spills" are still being detected at Platform B and said it will make efforts to clean up the spills before the deadline, Xinhua News Agency reported on Sunday.

The administration also ordered ConocoPhillips to provide a report by an independent evaluation authority once the leaks have been stopped and the spills contained.

Pollutants from the oil spill have been found on beaches in North China's Hebei province, and fisheries there are complaining that the disaster has caused the death of a large number of scallops.

"According to our statistics, about 70 percent of the scallops have died due to the oil leak, with economic losses reaching at least 200 million yuan ($30 million)," Yang Jizhen, chairman of the Laoting Fisheries Association, told China Daily.

About 30 boxes of dead scallops have been collected and stored as evidence since July 17, Yang said.

Around 160 households in Laoting county in the province rely on fisheries and related work for their livelihoods and they are planning to file a lawsuit against ConocoPhillips, the operator of the Penglai oilfield and its partner, China National Offshore Oil Corp, he added.

Qi Yuxiang, deputy director of the Laoting aquatic product bureau said they are checking every household to calculate the losses, but he is more worried about the potential long-term effects on exports. Aquatic products in Laoting are exported to Japan and the Republic of Korea.

According to statistics released by the administration on July 12, 4,240 sq km of coastal waters have been contaminated by the leak.

The administration ordered Houston-based ConocoPhillips to shut down production at the two platforms on July 13 because of the company's inability to contain the oil leaks at platforms B and C.

The company has estimated that about 1,500 to 2,000 barrels of oil and oil-based drilling fluids have been released into the sea.