China's ocean watchdog urged ConocoPhillips China, the company responsible for a pair of oil leaks off China's northeast Bohai Bay, to apologize to the public for its slow cleanup.

The American energy giant should explain its delay in finding additional oil-based drilling mud in the seabed and apologize to the public and the government, the North China Sea Branch of the State Oceanic Administration said on Wednesday.

It required the company to give a comprehensive assessment report on the cleanup process of the oily mud with details on the mud's area, thickness and amount, including the cleaned and to-be-cleaned parts, the measures for cleanup and the prevention of leaks.

ConocoPhillips responded on Wednesday by saying about 269 cubic meters (1,695 barrels) of oil-based mud has been recovered so far with about 900 personnel and more than 30 vessels involved in the response efforts.

The new finding will push the total amount of oil and oil-based drilling mud released past the previous estimate of 1,500 barrels.

Earlier, the State Oceanic Administration had asked ConocoPhillips to finish the seabed cleanup by Monday this week, give an assessment report on Wednesday and complete the whole cleanup before Aug 31.

Apparently, the deadline for the seabed cleanup cannot be met with the additional discovery of the oily mud on Aug 3, one day after the deadline was set.

John McLemore, ConocoPhillips's spokesman, told China Daily via email earlier that the cleanup may take longer than planned, which is likely with the discovery of the additional mud.

Although the company said full efforts have been taken, the North China Sea Branch has been increasingly critical of the company's "inefficient and temporary cleanup".

An anonymous official from the branch said the bad attitude from ConocoPhillips China showed that the punishment for leaks is not serious enough - the maximum punishment is only 200,000 yuan ($30,800) - and the company is showing a lack of social responsibility for China's marine environment.

"China is weak in supervision over marine development, especially the offshore oil exploration operated by multinational corporations," he said, adding that supervisors only go to offshore platforms once or twice a year.

Improving the marine environment law is urgent in protecting the fragile ocean biosystem, he added.

After the leak, all three provinces and one municipality around the bay - Hebei, Shandong, Liaoning and Tianjin - have reported fresh oil belts in seawater or dried oil drops ashore.

About 3,240 square kilometers of seawater were polluted at the peak of the leak, according to statistics from the State Oceanic Administration.

People in affected areas blamed the leak for losses in the tourism and fishing industries, with Laoting, a county in Hebei province, expected to face estimated economic losses of more than 200,000 yuan, the local fisheries association said.

Many environmentalists are calling for transparency and are blaming ConocoPhillips for hiding the truth.

Zhong Yu, senior action coordinator from Greenpeace, an international environmental organization, told China Daily that without details about the cause of the leak, the affected area and the current situation near the leak, it is hard to estimate possible environmental damage.

"The marine pollution caused by leak will last for decades," she added.