The government has described the leak as ‘substantial’ and estimates that it could be several hundred tonnes An oil spill in the North Sea is estimated to amount to several hundred tonnes, making it the biggest such leak in more than a decade, according to UK government figures. The spill – far greater than annual totals dating back to 2001 – was described as “substantial” by the Department of Energy and Climate Change (Decc). The total amount of oil discharged into the North Sea in 2009 was 50.93 tonnes. Shell, which operates the Gannet Alpha platform about 112 miles east of Aberdeen, said the subsea well was shut on Wednesday, but it has not confirmed the quantity of the leak. A Decc spokesman said the energy firm is still trying to “completely halt” any further leakage. The spokesman said: “Although small in comparison to the Macondo, Gulf of Mexico, incident, in the context of the UK continental shelf, the spill is substantial – but it is not anticipated that oil will reach the shore and indeed it is expected that it will be dispersed naturally. “The UK continental shelf oil spill record is strong, which is why it is disappointing that this spill has happened. We take any spill very seriously and we will be investigating the causes of the spill and learning any lessons from the response to it.” He added: “Current estimates are that the spill could be several hundred tonnes. “However, it is always very difficult and takes time to get an accurate assessment of the size of a spill and this is subject to ongoing revision. “So these estimates are subject to continuing analysis and change. The Maritime and Coastguard Agency are making twice-daily flights to monitor the situation.” Mick Borwell, from the offshore industry body Oil and Gas UK, said he is convinced the energy firm is doing all it can to tackle the problem. “Any oil company operating in the UK takes oil spill, any volume of oil spill, very seriously,” he told BBC Radio Scotland’s Good Morning Scotland programme. “It’s one of the reasons we have one of the most robust response mechanisms to oil spills. “I think this level of spill is not normal for the UK continental shelf and I’m absolutely convinced that Shell are doing what they need to do to deal with it.” He added: “It’s important to remember that oil degrades and disperses very quickly in the marine environment, more so as the weather conditions increase. “The UK strategy for dealing with an oil spill is to wait and see how it behaves.” Environment groups raised their concerns for wildlife in the area. Stuart Housden, director of RSPB Scotland, said: “We know oil of any amount, if in the wrong place, at the wrong time, can have a devastating impact on marine life. Currently thousands of young auks – razorbills, puffins and guillemots – are flightless and dispersing widely in the North Sea during late summer. So they could be at serious risk if contaminated by this spill. “If Shell is confident that the situation is now under control we must now start to assess what happened and make sure the relevant precautions are in place to stop this happening again.” Oil spills Oil Oceans Oil Energy Fossil fuels Oil and gas companies Energy industry Royal Dutch Shell Wildlife Marine life Birds guardian.co.uk