Tehran meanwhile signaled its resolve to expand its enrichment capability by detailing plans to build advanced centrifuges – the machines that enrich uranium.

European powers have been scrambling to salvage the agreement they signed in 2015 since U.S. President Donald Trump pulled Washington out last month and said he would reimpose far-reaching U.S. sanctions on Iran.

Foreign and finance ministers from those three countries – France, Britain and Germany – have written to U.S. officials to stress their commitment to upholding the pact, and to urge Washington to spare EU firms active in Iran from secondary sanctions. Read more