The US is sending two top negotiators to Geneva for direct talks with Iranian officials over Tehran’s nuclear programme.
Deputy Secretary of State William Burns and Undersecretary of State for Political Affairs Wendy Sherman are set to enter talks on Monday and Tuesday.
An interim deal reached in November by Iran and six world powers – the US, Russia, China, Britain, France and Germany – limited Iran’s uranium enrichment programme.
In exchange, some penalties imposed against Iran were eased. But sanctions such as those targeting Iran’s oil imports have remained in place.
The nuclear talks are set to resume on June 16. There is an informal deadline of July 20 for a comprehensive deal.
The West suspects Tehran is seeking atomic weapons. Iran denies that, saying its aims are peaceful.