China's maritime authorities have set up a working group to assist with compensation claims for the oil leaking in North China's Bohai bay as the time set for the US company ConocoPhillips to clean up the spill hits deadline day, the Beijing Times reported.

The State Oceanic Administration (SOA) said the leak at Penglai 19-3 oil field, the largest offshore oilfield in China, has caused severe pollution.

Concerned parties, including the government and fishermen in 16 provinces and cities in the affected area, have the right to lodge claims for compensation according to the law.

The assessment of the ecological pollution resulting from the spill has been completed, said Fang Jianmeng, SOA’s Beihai branch, on Tuesday. Fang said the administration was compiling a report based on the assessment, which can provide a legal basis for compensation claims.

ConocoPhillips said on Monday it had cleaned up 99 percent of the mineral oil-based drilling mud near Platform C at Penglai 19-3 oil field.

However, the company's statement raised questions from environmental experts and lawyers.

The US company has been widely criticized for its slow response to the oil spill, which has lasted for more than two months and has still not been stopped.

In addition, ConocoPhillips did not apologize to the Chinese public until Aug 24, more than two months after the oil spill was discovered.

The company has also not worked out a compensation plan for the damage the incident has caused to the ocean environment and the nearby fishery industry.