Oil giant Shell has defended its safety regulations in the wake of calls to restrict the company\'s operations in the North Sea. More than 200 tonnes of oil spilled into the water after a leak was detected from a flowline to Shell\'s Gannet Alpha platform, about 112 miles east of Aberdeen, Scotland, on August 10. It was the worst oil spill in the region in more than a decade. Last Friday, divers closed the relief valve from which oil had been seeping at a rate of less than one barrel a day and yesterday Shell said that no oil had seeped out since the valve was closed. Environmental organisation \"WWF Scotland\" called on the UK Government to restrict all of the company\'s operations in the North Sea until an independent audit had been carried out on its installations. In a statement Monday, Dr. Richard Dixon, director of WWF Scotland, said: \"We also need to be reassured about the state of other companies\' ageing equipment in the North Sea if we are to avoid a repeat of the Gannet Alpha spill. \"We shouldn\'t be going after oil in difficult and sensitive waters anywhere in the world, but if there is some drilling in such locations, Shell\'s track record clearly shows that they are not fit to be part of that exploration.\" For its part, Shell said in a statement that the audit, carried out in 2003, had led to a \"huge investment programme.\" A spokesman said: \"Safety is Shell\'s foremost priority at all times. \"As part of that commitment, in 2004 Shell initiated a 1.2 billion dollars (728 million pounds) project to upgrade our assets in the North Sea. This has been completed. \"This year alone, we plan to invest approximately 600 million dollars (363 million pounds) in our assets in the region\".