China has launched safety inspections of all its offshore petroleum exploration and production bases, following an oil spill in the nation\'s northern Bohai Bay, the government said Sunday.All offshore oil companies were called on to inspect their fixed and mobile platforms, floating production, storage and offloading units, underwater pipelines and onshore oil terminals, the government said.The inspections started on September 10 and will continue until November 10, after which government experts will review the results of the checks, China\'s State Administration of Work Safety said on its website. The inspections come after the government ordered an investigation into the Bohai Bay spill, which began in early June at the Penglai 19-3 facility, China\'s largest offshore oil field that is run by US giant ConocoPhillips.The spill had polluted an estimated 5,500 square kilometres (2,200 square miles) of water as of Monday, the official Xinhua news agency said. ConocoPhillips said it halted production on September 3.The US giant, which has denied any cover-up, says the equivalent of 3,200 barrels have leaked into the sea. It has defended its record over the spill but accepted responsibility for the damage caused.It co-owns the oilfield with the state-owned China National Offshore Oil Corp (CNOOC).