China's ocean watchdog sharply criticized ConocoPhillips China Inc on Wednesday for not having an effective means of preventing oil leaks.

It also warned of new leak risks in an oilfield that was the source of a sheen that appeared in a bay of the Yellow Sea in June.

The leak has polluted at least 4,240 square meters of seawater in Bohai Bay, in the northern part of the Yellow Sea, and has proved to be a "great threat" to the environment there, according to a notice released on the official website of the State Oceanic Administration on Wednesday.

To clean up the bay and to ensure the oil found there is obtained in a safe and sustainable manner, the administration asked ConocoPhillips China to immediately suspend the operations of two platforms at the Penglai 19-3 Oilfield, the source of the leak, and eliminate the risk of fresh leaks as soon as possible, according to the notice.

The field may not be put into production again until the oil leak has been completely stopped, it said.

The State Oceanic Administration also required ConocoPhillips China to regularly report about the spill to the administration and to release information about the incident to the public.

After a new oil sheen was detected in satellite images on Sunday, the State Oceanic Administration has criticized twice in three days what it described as the company's slow responses to leaks.

ConocoPhillips China has said previously that the work to clean up the bay is almost finished, but admitted on Tuesday that "minor residual seepage" may continue and only diminish over time.

ConocoPhillips said in an email reply to China Daily that the company will comply with all orders from the SOA.

"We have shut down production from Platform B and C until further direction is provided from SOA," the company said.

The total production from these two platforms was approximately 47,000 barrels per day, which represents a third of the production from the entire PL 19-3 field.

The company said it is currently re-evaluating all its development plans for the field to ensure that the kind of seepage does not occur again.

The Penglai 19-3 Oilfield is the largest offshore oilfield in China. ConocoPhillips China holds a 49-percent stake in the project and the China National Offshore Oil Corp holds the rest.

Incensed at the spill's harm to the environment and the slow release of information concerning the incident, the public and environmental organizations have been quick to express criticism.

Feng Yongfeng, founder of the Green Beagle - an environmental organization - told China Daily he is "shocked" to know fresh oil is leaking into the sea and said the State Oceanic Administration should bring ConocoPhillips China's operation at the site of the leak to a halt.

Eleven environmental organizations have expressed a desire to file a joint lawsuit against the company and its partner, China National Offshore Oil Corp, calling them responsible for the leak in Bohai Bay.

Hindering them from taking that step, though, is a lack of information about the incident, either from the companies themselves or the State Oceanic Administration, said Wang Haijun, a lawyer at the Beijing Deheng Law Firm, which was representing the environmental groups on Wednesday.

"We can only get information from the media, which cannot be used as evidence in court," Wang said. "That is our biggest barrier so far."