US President Donald Trump says that Iran has "sort of" agreed to the terms of a nuclear deal with the United States.

Trump described the latest talks between the two countries, which ended on Sunday, as "very serious negotiations" for "long-term peace".

Earlier, an adviser to Iran's supreme leader told NBC News that Tehran was willing to make concessions on its nuclear programme in exchange for the lifting of sanctions.

The US has insisted that Iran must scrap its uranium enrichment to prevent the country developing nuclear weapons - though Iran insists its nuclear activities are entirely peaceful.

Speaking on Thursday in Qatar, on the second stop of his multi-day Gulf tour, Trump said that a deal was close on Iran's nuclear programme and suggested a military strike on Tehran's sites could be avoided.

"We're not going to be making any nuclear dust in Iran," Trump said after a meeting in Doha with business leaders.

"I think we're getting close to maybe doing a deal without having to do this.

"You probably read today the story about Iran. It's sort of agreed to the terms."

The president did not specify which remarks he was referring to, but an adviser to Iran's supreme leader Ayatollah Ali Khamenei, Ali Shamkhani, said in a US media interview that Tehran was willing to accept far-reaching curbs on its nuclear programme.

Shamkhani told ABC News that Iran would give up stockpiles of highly enriched uranium as part of a deal in which the US lifts sanctions.

The latest talks over Tehran's nuclear programme finished on Sunday, with both sides agreeing to meet again.

US Middle East Envoy Steve Witkoff said they were encouraging, while Iran's Foreign Minister Abbas Araghchi described them as "difficult but useful".

Trump pulled out of a previous nuclear agreement between Iran and five other world powers in 2018.

He previously warned of possible military action against Iran's nuclear facilities if the fresh set of talks, which began in April, did not succeed.

A senior US official said the latest discussions lasted more than three hours, adding: "Agreement was reached to move forward with the talks to continue working through technical elements.

"We are encouraged by today's outcome and look forward to our next meeting, which will happen in the near future."