The talks suggest both sides are buying time. For Iran’s leadership, an agreement could unlock billions in frozen assets and reduce sanctions pressure.

Iran has demanded that the United States clarify exactly how sanctions will be lifted if the two sides are to reach a new agreement on Tehran’s nuclear programme. Ministry of Foreign Affairs spokesman Esmail Baghaei made the comments on Monday,

Iran said Monday it will not accept a nuclear agreement that deprives it of what it called "peaceful activities", a reference to uranium enrichment, as it pressed the United States for guarantees it would drop sanctions.