China's State Oceanic Administration has begun evaluating ConocoPhillips's clean-up operation in the Bohai Bay.

The US-based company has submitted a report to the Administration claiming it's accomplished its tasks of finding and plugging all the leaks in the oil field by the 31st of August deadline.

A surveillance ship dispatched by the Administration aimed to reach the spill site earlier Thursday, but strong gales and giant waves aborted the mission. It will sail again when the weather improves.

But the Administration says aerial surveillance still shows traces of oil spill near Platform C. The Administration says it will publish its evaluation report when it's finished, together with any further requirements on the company.

ConocoPhillips has so far made no comment on growing public skepticism about its clean-up work.

The company says it's been assessing the impact of the oil spill to the environment, and it's still unable to form an accurate assessment about the extent of the damage and the compensation.