Top Iranian and U.S. negotiators began a new round of indirect talks on Saturday to hammer out a deal curbing Tehran's nuclear programme, while U.S. President Donald Trump signalled confidence in clinching a new pact that would block Iran's path to a nuclear bomb.

Experts met first on Saturday and then indirect negotiations between Iranian Foreign Minister Abbas Araqchi and Trump's Middle East envoy Steve Witkoff began in Muscat through Omani mediators, a week after a second round in Rome that both sides described as constructive.

The experts-level indirect meetings in Muscat, which were continuing throughout Saturday, are aimed at drawing up a framework for a potential nuclear deal.

An Iranian official, briefed about the talks, told Reuters that the experts-level negotiations "are difficult, complicated and serious", without elaborating.

Trump has spent the beginning of his second term in office trying to broker deals on some of the world's biggest conflicts and crises, including Russia's invasion of Ukraine, Israel's assault on Gaza and the thorny issue of Iran's nuclear programme.

The Islamic Republic, for its part, has signalled it is keen to get sanctions' relief as its economy continues to suffer, and after more than a year of military setbacks at the hands of its regional foe Israel.

"Iran remains steadfast in its principled stance on the need to end unjust sanctions and is ready to build confidence about the peaceful nature of its nuclear programme," Foreign Ministry spokesman Esmaeil Baghaei told reporters in Oman.

Trump, in an interview with Time magazine published on Friday, said "I think we're going to make a deal with Iran", but he repeated a threat of military action against Iran if diplomacy fails.

Shortly after Araqchi and Witkoff started indirect talks, Iranian state media reported a massive explosion at the country's Shahid Rajaee port near the southern city of Bandar Abbas, injuring hundreds of people.