The UK prime minister has hailed an agreement by the UK’s Overseas Territories and Crown dependencies to sign up to a tax evasion clampdown.
David Cameron said it was a “very positive step forward” ahead of the G8 meeting, which starts on Monday.
But sources from the Crown Dependencies told the BBC a proposed register of companies, revealing the true owners, may not work.
They say it does not include trusts and the UK business community may object.
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 a meeting at No 10 on Saturday.
Many regard the islands and outposts as tax havens, although that is a label they strongly dispute.
They have agreed to sign up to the Multilateral Convention on Mutual Assistance in Tax Matters – an initiative led by the Organisation for Economic Cooperation and Development (OECD).
We are an open and transparent jurisdiction
They have also agreed to publish national action plans on beneficial ownership, detailing the true owners of so-called “shell” companies.