China will start "overall and thorough" safety checks on offshore oil exploration and production to eliminate risks in the wake of oil spills in the country's northern Bohai Bay, the work safety authority said Saturday.

The checks, which starts from September 10 to December 10, will be applied to all offshore oil exploration and production, the State Administration of Work Safety said in a circular addressed to oil companies on its website.

The companies include China National Petroleum Corporation, China Petrochemical Corporation, China National Offshore Oil Corporation, ConocoPhillips China, Kerr-McGee China Petroleum Ltd., Roc Oil (Bohai) Company, CACT Operators Group, Husky Oil China Ltd., Shanghai Petroleum Co., Energy Development Corporation (EDC) China and Tincy Group Energy, the statement said.

The administration urged these enterprises to conduct self-examinations on their offshore fixed and mobile platforms and floating production storage and offloading units, submarine pipelines and onshore oil terminals in two months till November 10. They should file result reports before November 20.

The authority's officials, joined by experts, will launch inspections from late November, the statement said. The checks cover well control amid drilling operation, safety management during production, facilities, and management over extreme weather, it added.

The order came after the State Council on Wednesday called for strengthened monitoring and management of the marine environment as well as safety checks over the country's ocean oil fields to toughen safety measures and erase potential risks.

The decision was made after oil spills at an offshore oil field run by U.S. oil giant ConocoPhillips have polluted more than 5,500 square km of sea water in the Bohai Bay since June.

The central government also imposed restricts on new petrochemical projects and ban reclamation projects in the bay for environmental concerns.

China has stepped up efforts to explore and materialize offshore resources to seek more dependence of the marine industries as a strategic development move. In its 12th Five-Year Plan, the government advocates greater scientific and systematic utilization of marine resources and coastal areas as energy demand soars.