British Prime Minister David Cameron was on Thursday to announce that a list of the owners of shell companies often used as a shield against tax will be made public. Cameron will vow a \"relentless\" fight against companies evading tax and say that the use of shadowy shell firms has resulted in \"downright illegality\" when he addresses the Open Government Partnership summit in London. \"For too long a small minority have hidden their business dealings behind a complicated web of shell companies -- and this cloak of secrecy has fuelled all manner of questionable practice and downright illegality,\" he will say, according to extracts released by his Downing Street office. \"Not only is this hugely unfair to the millions of hard-working people in Britain who pay their tax but it\'s also bad for business. \"To keep corporate taxes low, you\'ve got to keep corporate taxes coming in. As I\'ve put it, no tax base - no low tax case. \"So that\'s why we need to shine a spotlight on who owns what and where money is really flowing,\" he will add.