France, April 12 -- The United States and Iran held "constructive" talks on Tehran's nuclear programme on Saturday and agreed to meet again as President Donald Trump threatens military action if they fail to reach a deal.

Oman's foreign minister acted as an intermediary in the high-stakes talks in Muscat, Iran said. The Americans had called for the meetings to be face-to-face.

However, the negotiators also spoke directly for "a few minutes", Iran's foreign ministry said. It said the talks were held "in a constructive and mutually respectful atmosphere".

Disagreement over the format indicated the scale of the task facing the long-term adversaries, who are seeking a new nuclear deal after Trump pulled out of an earlier agreement during h...