Anti-poverty campaigners tonight urged David Cameron to build on his agreement with Britain's network of Crown dependencies and overseas territories to forge a global deal on tackling tax evasion.
The Prime Minister hailed the agreement struck in talks in Downing Street with the leaders of the ten offshore jurisdictions on the exchange of information between tax authorities as a "very positive step forward".
He said he hoped it would strengthen his hand in negotiations at next week's G8 summit in Northern Ireland where he has placed tax transparency at the top of the agenda.
ITV News' Political Correspondent Carl Dinnen reports:
Bermuda, the British Virgin Islands, the Cayman Islands, Gibraltar, Anguilla, Montserrat, the Turks and Caicos Islands, Jersey, Guernsey and the Isle of Man were all represented at the talks.
Many of the islands and outposts are regarded as tax havens - a description they bitterly dispute - where wealthy individuals can shield their fortunes from the prying eyes of onshore tax authorities.
Under the agreement, they will trial an international pilot programme which will see the automatic exchange of information between tax jurisdictions while signing up to the Organisation for Economic Co-operation and Development's (OECD) convention on mutual assistance on tax.
They also agreed to publish national action plans on beneficial ownership - declaring the true owners of so-called "shell" companies.
Earlier, in a further move to show that he was cleaning up his own backyard, Mr Cameron announced plans to establish a register of beneficial ownership in the UK.