QINGDAO - Chinese maritime authorities have urged ConocoPhillips China (COPC) to apologize to the public for its prolonged treatment of oil leaked from two of its platforms in northeast China's Bohai Bay.

The North China Sea branch of the State Oceanic Administration has asked COPC to explain the reason why it failed to clean up oil-based mud on the seabed timely and urged it to make an apology, according to the branch Wednesday.

The branch has also urged the company to hand in a comprehensive assessment report concerning its clean-up efforts.

The company missed a deadline for recovering the oil-based mud leaked from Platform C of Penglai 19-3 oilfield on Sunday as workers found new mud during the clean-up work.

The COPC first reported the two oil spills in the Penglai 19-3 oilfield to authorities in June. The oil spills have been seen spreading to beaches in the northern Hebei Province and northeastern Liaoning Province. The spills have been blamed for losses in the provinces' tourism and aquatic farming industries.

Oil-drilling operations in the field are jointly conducted by ConocoPhillips China and the China National Offshore Oil Corporation (CNOOC), the country's largest offshore oil producer.