Fifty-one countries have signed an agreement to share financial data and boost efforts to crack down on tax evasion.

The standard agreed upon in Berlin on Wednesday was developed by the Organisation for Economic Co-operation and Development in consultation with the world's top 20 economies.

The countries that signed include most European Union nations, as well as traditional tax havens like Liechtenstein, the British Virgin Islands and the Cayman Islands. They will begin automatically exchanging data collected by financial institutions as early as 2017, the OECD said. Other countries have indicated they will join the accord later.

The United States hasn't signed but says it will share information as part of bilateral deals.

Britain's treasury chief, George Osborne, says the new treaty "strikes a blow on behalf of hard-working taxpayers."