MUSCAT: The United States and Iran reported progress in their latest round of nuclear talks on Saturday and agreed to meet again next week as they pursue a deal that could help ease soaring Middle East tensions.

A US official called the talks `positive and productive`, and Iran`s top diplomat said the two sides will study how to narrow their differences on a range of subjects before next week`s fourth round.

The highest-level contact in years between the long-time foes is targeting a new dealthat would stop Iran developing nuclear weapons an objective Tehran denies pursuing in return for relief from sanctions.`There is still much to do, but further progress was made on getting to a deal,` the senior US official said on condition of anonymity, adding that thenext talks would be in Europe.

Iranian Foreign Minister Abbas Araghchi called Saturday`s talks, which included technical-level teams for the first time, `serious and businesslike`. `There are differences both in the major issues and in the details,` he told Iranian state TV. `Until the next meeting, further studies are to be conducted in the capitals on how to reduce differences.

FM Araghchi said, `I think our progress has been good so far. I am satisfied with the process of the negotiation and its speed. I think it is proceeding well and satisfactorily.

US President Trump pulled out of an earlier, multilateral nuclear agreement with Iran.

`Minute details` US special envoy Steve Witkoff again led the Americandelegation while Michael Anton, the State Department`s head of policy planning, headed the US expert-level negotiators.

Deputy foreign ministers Kazem Gharibabadi and Majid Takht-Ravanchi led Tehran`s technical team, according to Iran`s Tasnim news agency.

The delegations were in separate rooms and communicated in writing via the hosts, Iranian foreign ministry spokesperson Esmaeil Bagaei and Araghchi said.

`The expert and technical talks... reached the stage of minute details about mutual demands and expectations,` an Iranian state TV reporter said.

Iran`s defence and missile capabilities were not discussed, Bagaei told state TV, while an Iranian negotiator said the talks were `uniquely aboutsanctions and nuclear questions`, according to Tasnim.

FM Araghchi had earlier expressed `cautious optimism`, saying this week: `If the sole demand by the US is for Iran to not possess nuclear weapons, this demand is achievable`.

The talks coincided with a major blast at Iran`s Shahid Rajaee port that injured hundreds of people and killed at least four, state media reported.

The port`s customs office said it probably resulted from a fire in a storage depot.

Before the talks, Trump, in an interview published on Friday by Time magazine, reiterated his threat of military action if a deal fell through.

But he added that he `would much prefer a deal than bombs being dropped`.The talks began in Muscat a fortnight ago and continued in Rome last Saturday.

Iran currently enriches uranium to 60 per cent, far above the 3.67pc limit imposed by the 2015 deal, from which the US had pulled out during the first term of Trump, but still below the 90pc threshold required for weapons-grade material.

Last week, US Secretary of State Marco Rubio urged the three European states to decide whether to trigger the `snapback` mechanism under the 2015 agreement, which would automatically reinstate UN sanctions on Iran over its non-compliance.

The option to use the mechanism expires in October. Iran has warned it could withdraw from the nuclear NonProliferation Treaty if the snapback is triggered. -AFP