Documents list companies that caused more than 100 potentially lethal – and largely unpublicised – leaks in 2009 and 2010
Serious spills of oil and gas from North Sea platforms are occurring at the rate of one a week, undermining oil companies' claims to be doing everything possible to improve the safety of rigs.
Shell has emerged as one of the top offenders despite promising to clean up its act five years ago after a large accident in which two oil workers died.