Cameron announces international deal to prevent tax evasion after meeting with British territories in Downing Street Bermuda now agrees to sign up to international register of companies Prime Minister hails agreement as an 'very positive step forward' But aid organisations raise fears of two-tier system locking poor nations out David Cameron today announced he had secured agreement with Britain's network of overseas territories and Crown dependencies to sign up to a new clampdown on tax evasion. The Prime Minister has been holding high level talks in Downing Street ahead of next week's G8 Summit at Lough Erne, Northern Ireland where tax evasion is one of the leading topics for discussion. Getting agreement from Britain's overseas territories, among them Bermuda, the British Virgin Islands, the Cayman Islands, Gibraltar, the Channel islands and the Isle of Man is seen as a crucial step in the forthcoming negotiations. Tax haven: crown dependency Bermuda claimed it complied with international tax law already so did not need to sign the EU-US backed register Britain's overseas territories make up one fifth of all the tax havens - and are among the largest and most sophisticated - in the world. Until today Bermuda was refusing to sign up to the register backed by Britain, the European Union, United States and Organisation for Economic Cooperation and Development. Bermuda had claimed it already met many of the provisions Mr Cameron wants the tax havens to sign up to and was not ready to commit to signing the convention. Even after the announcement several overseas territories said the still have misgivings about whether an international register of companies and their beneficial owners will work. The Prime Minister hailed the agreement as a "very positive step forward" which would strengthen his hand in talks with the other G8 leaders. He is hoping to reach agreement from the leaders of all the G8 nations to a series of actions aimed at promoting transparency and exchange of information between tax jurisdictions. Done deal: the Prime Minister moved a step closer to securing a deal on tax evasion after securing the agreement of Britain's overseas territories to sign up to a new international register 'Let's be clear why this tax issue matters. If companies don't pay their taxes or individuals don't pay their taxes we all suffer as a result,' Mr Cameron said. It is important we are getting our house in order. What the Crown dependencies - places like Jersey and the Isle of Man, and the overseas territories - places like the Cayman Islands - have signed up to is basically the existing and the new standards for exchanging tax information. That is absolutely vital. 'It is a very positive step forward and it means that Britain's voice in the G8 and the campaigning on this issue around the world for proper taxes, proper companies and proper laws ... will be stronger.' Despite the agreement, Mr Cameron still has to win over a key opponent in the Canadian Prime Minister Stephen Harper, who is not convinced by the proposals being put forward by Britain, the European Union and the US. Russia President Vladimir Putin could also prove to be a roadblock to the reforms. International aid organisations have also been quick raise concerns about the British proposals which they say amount to a plan A and a plan B. Yesterday they delivered a letter to Mr Cameron and the other G8 leaders with 189 signatories warning the plan B proposal would effectively lock out developing nations from the register and deny them access to crucial information they need to collect tax efficiently. Under the original plan all countries would have been able to access the register but the under the watered down proposal only internationally recognised tax authorities, such as HMRC would be able to access the register. The letter warns this would mean: "excluding developing countries that wish to join such an international system either directly or de facto through an unfeasible burden of reciprocation of information - would in many cases freeze out those...worst hit by tax avoidance and evasion." A spokesman for the charity Action Aid, one of the signatories to the letter, said the plan B option would amount to betrayal of the world's poorest countries preventing them from collecting "desperately needed tax revenues that could be used to fund schools and hospitals."