BEIJING - China's maritime authorities have urged ConocoPhillips China to clean up the oil-polluted seabed in Northeast China's Bohai Bay by Sunday.

The North China Sea Branch of the State Oceanic Administration (SOA) also criticized the company for not acting efficiently enough to deal with the spill, which began June 4 in the bay's Penglai 19-3 oilfield.

In a notice issued on Monday, the branch urged ConocoPhillips China to appropriately dispose of contaminants to avoid further pollution and to submit a report on its cleanup work by next Wednesday.

"We have every intention of meeting both requests - on the 7th (Sunday) and the 10th (next Wednesday)," ConocoPhillips spokesman John McLemore told China Daily via email.

On Friday, the SOA ordered the company to stop the leaks, clean up polluted areas and conduct a thorough investigation to eliminate possible further oil spills before Aug 31.

ConocoPhillips China spokesperson Donna Xue told China Daily the company is "working around the clock on the cleanup work" and is working with the SOA in meeting the requested deadline.

The company estimated on July 13 - the latest information available on its website - that the aggregate amount of the spill was around 1,500 barrels (240 cubic meters) of oil and oil-based drilling fluids.

Using remote satellites, patrol planes and boats to survey the oilfield last week, the SOA identified a polluted area of approximately 1,200 square km.

According to the latest monitoring information released by the North China Sea Branch of the SOA, small-scale oil belts and oil seepages have been detected in Platform B and C in the Penglai 19-3 oilfield, where operations have been suspended since mid-July.

In response, ConocoPhillips said on Monday that the limited, fluid removal process is continuing for two wells from Platform B, which can reduce pressure in the reservoir - the source of the leak - and significantly lessen the likelihood of future seepage.

Fourteen divers recovered about seven cubic meters of oil-based drilling mud from the seabed around Platform C on Sunday, the statement said.

It added that ConocoPhillips sent 102 people on Sunday to walk along about 96 km of shoreline on Bohai Bay, and 16 vehicles surveyed nearly 1,500 km of shoreline. They collected materials and tested them to see if any matched the chemical makeup of the oil leaking from the Penglai oilfield.

However, the company's response has failed to satisfy environmental groups in China.

Twelve environmental organizations released a public letter on Monday calling for more transparency in the environmental assessment process.

The letter also asked the SOA to draft a request for compensation from ConocoPhillips and its partner China National Offshore Oil Corp.

The affected areas have expanded to the three provinces surrounding Bohai Bay: Liaoning, Hebei and Shandong.

According to monitoring results released by the SOA, oil from the incident was found ashore in Liaoning's Suizhong county and Hebei's Tangshan city in late July. Dead fish and scallops were also reported in Shandong and Hebei provinces.

Yang Jizhen, chairman of the Laoting Fisheries Association in Hebei, said on Tuesday that about 70 percent of the scallops the association's members raised have died due to the leak and their economic losses were estimated to exceed 200 million yuan ($31 million).

"More are dying," he sighed.