Marine authorities yesterday began checking ConocoPhillips' sealing of leaks and clean-up of oil spills in the Bohai Sea, but bad weather prevented them from delivering a report yesterday as some officials had expected.

A spokeswoman for the State Oceanic Administration's North China Sea Branch in Qingdao, Shandong , said yesterday that the inspection fleet had encountered strong winds and high waves near the two production platforms that were crippled by a series of oil spills since June.

She said the administration was trying to contact its employees at the inspection sites after hearing about the bad weather. She said a report might not be ready yesterday but it would be released as soon as possible. Xinhua reported that the authorities had abandoned the inspection yesterday morning.

On Wednesday, ConocoPhillips said it had submitted a comprehensive report about the oil spills, and concluded that they had sealed all the leaks and cleaned up all traces of oil from the ocean surface before midnight on Wednesday, the deadline specified by the administration.

The American company - which operates Penglai 19-3, the mainland's largest offshore oilfield, in partnership with China National Offshore Oil Corporation - said it had provided its assessment on the causes of the leaks, on the technical details of the sealing methods, and on the measures to be used in its future operations to prevent similar incidents. The administration said yesterday that it had received the report and would examine it carefully with a team of experts. It did not say how long it would take.

The administration has chosen four law firms to provide legal services as they bring ConocoPhillips to court for economic losses and environmental damages, Caixin Century magazine reported yesterday.