Iran’s Foreign Minister Abbas Araqchi has landed in Moscow to deliver a message from the country’s Supreme Leader, Ali Khamenei, to Russian President Vladimir Putin, Iranian state media has reported.

Araqchi's Telegram account posted a video of him arriving in Moscow on Thursday.

US President Donald Trump has repeatedly threatened Iran with bombing and secondary tariffs if Tehran does not come to an agreement with Washington over its disputed nuclear program, and the United States has moved additional warplanes into the region.

The US and Iran held talks in Oman last weekend that both sides described as positive and constructive.

Ahead of a second round of talks set to take place in Rome this weekend, Araqchi said on Wednesday that Iran's right to enrich uranium is not negotiable.

Western powers say Iran is refining uranium to a high degree of fissile purity beyond what is justifiable for a civilian energy programme and close to the level suitable for an atomic bomb.

Iran has long denied seeking nuclear weapons allegations.

Russia has said that any military strike against Iran would be illegal and unacceptable.

The Kremlin on Tuesday declined to comment when asked if Russia was ready to take control of Iran's stocks of enriched uranium as part of a possible future nuclear deal between Iran and the United States.