Lausanne: The US, Iran and five other world powers on Thursday announced an understanding outlining limits on Iran's nuclear programme so it cannot lead to atomic weapons, directing negotiators toward achieving a comprehensive agreement within three months.
Reading out a joint statement, European Union foreign policy chief Federica Mogherini said a "decisive step" after more than a decade of negotiations had been achieved.
Iranian Foreign Minister Mohammad Javad Zarif followed with the same statement in Farsi.
US Secretary of State John Kerry and the top diplomats of Britain, France and Germany also briefly took the stage behind them.
In a tweet, Kerry said there was an agreement "to resolve major issues on nuclear program. Back to work soon on a final deal."
Mogherini said the seven nations would now start writing the text of a final accord. She cited several agreed-upon restrictions on Iran's enrichment of material that can be used either for energy production or in nuclear warheads. She said Iran won't produce weapons-grade plutonium.
Crucially for the Iranians, economic sanctions related to its nuclear programs are to be rolled back after the UN nuclear agency confirms compliance.
