Beijing: Chinese Premier Wen Jiabao ordered a "thorough" investigation into the leaks at China's biggest offshore oil field after ConocoPhillips apologised for the spills in the country's northern Bohai Bay.

Wen, at a State Council meeting on Wednesday, also called for immediate work safety checks on all offshore oil exploration and production, the government said.

Since June the Penglai 19-3 field has leaked 3,200 barrels of oil and drilling fluids into the bay, where PetroChina Co. and China Petroleum & Chemical Corp have onshore refining projects. The State Council, China's Cabinet, said it will restrict new petrochemical projects and ban land reclamation in the area, according to the statement.

"If the government were to approve new projects, they would approve the bigger ones by the state-owned companies," Shi Yan, a Shanghai-based analyst at UOB-Kay Hian Ltd, said. "Pollution from small private plants actually poses a bigger problem. In the end, we may see consolidation where the big state-owned companies buy the small independent refiners and petrochemical makers."

China Petroleum's parent plans to jointly invest $1 billion (Dh3.67 billion) with Saudi Basic Industries Corp. in a polycarbonate plant in Tianjin at Bohai Bay, the Riyadh-based company said yesterday, without specifying whether the project has been approved by the government.

The company known as Sabic already has a $3 billion petrochemical joint venture in the port city. Bohai is one of the three bays forming the Bohai Sea, the innermost gulf of the Yellow Sea. About 870 square kilometres of Bohai Bay was polluted by the Penglai spills, according to the official Xinhua News Agency.

Apology

The leaks at Penglai, which ConocoPhillips co-owns with CNOOC Ltd., were China's worst since a pipeline blast at Xingang port in Liaoning province caused about 11,000 barrels of oil to spill into the Yellow Sea in July last year.

CNOOC fell 1.3 per cent to HK$14.02 (Dh51.49) in Hong Kong trading as of the midday break, compared with the 0.8 per cent decline in the benchmark Hang Seng Index. Conoco-Phillips gained 2.5 per cent to $67.31 in New York on Wednesday.

ConocoPhillips was ordered to halt output at Penglai after "delays, negligence, cover-ups and cheating," the People's Daily, the Communist Party's official newspaper, wrote on Monday.