"An outline agreement on the future shape of Iran's nuclear programme has been reached after marathon talks with six major powers in Switzerland."
Under the deal, Iran will reduce its uranium enrichment capacity in exchange for phased sanctions relief.
US President Barack Obama said a "historic understanding" had been reached with Iran.
The world powers and Iran now aim to draft a comprehensive nuclear accord by 30 June.
Read more: The framework agreement was announced by the European Union and Iran after eight days of negotiations in Lausanne (BBC).