Iran and six world powers have failed for the second time this year to clinch a deal on Tehran’s nuclear programme.
They have given themselves until July to overcome a deadlock that has prevented them from resolving a dispute.
Philip Hammond, Britain’s foreign secretary, said significant progress had been made in the latest round of talks.
“Well it’s a disappointment but as you say, there has been momentum and there has been good will on both sides and the atmospherics are positive. So the decision we’ve taken today is to extend the joint plan of action, the freeze on Iran’s activity and the access that Iran has to some of its frozen assets for a period of seven months, to the end of June (2015), and to use that time to keep the foot on the gas, to keep going with these discussions.”
US Secretary of State John Kerry said the talks “are not going to get easier just because we extended them. They’re going to stay tough.”
The discussions, which have dragged on for more than a year, aim to set limits on Iran’s nuclear programme in return for ending sanctions that have weighed heavily on its economy.
Iran says its nuclear programme is for peaceful purposes.