Labour leader Ed Miliband has welcomed the move to establish a set of global standards to tackle tax evasion.
However, Mr Miliband also warned David Cameron that he must be prepared, if necessary, to get tough with any countries which refuse to comply.
Writing in The Independent, the Labour leader said Britain "needs to use all its considerable legal power and authority to ensure all the UK overseas territories and Crown dependencies which act as tax havens sign up".
More top news
Sir Nicholas Winton, who rescued 669 children from the Nazis, didn't tell anyone about his exploits for 50 years - not even his wife.
Police believe one of the West's most infamous criminals, timeshare fraudster John Palmer, was murdered.
Police say a 'disaster was averted' when officers caught a suspected drink-driver who tried to drive the wrong way up the M6.