Iran and the United States reached an understanding on the main "guiding principles" in a second round of nuclear talks in Geneva on Tuesday but work still needs to be done, Iranian Foreign Minister Abbas Araqchi said.

The United States should immediately desist from threatening the use of force against Iran, Araqchi said on Tuesday.

‘A new window of opportunity has opened, we are hopeful negotiations will lead to a sustainable and negotiated solution; any sustainable agreement must ensure full recognition of Iran's legitimate rights’, Araqchi added.,

The progress does not mean an agreement will be reached soon but the path has started, he told Iranian media after the talks concluded.

Araqchi was speaking at a disarmament conference in Geneva after talks were held between U.S. and Iranian representatives in the western Swiss city earlier in the day.

Iranian state media reported earlier that Iran would temporarily shut part of the Strait of Hormuz, a vital global oil supply route, as it held talks over its nuclear programme with the United States, which has sent a battle force to the Gulf region to press Tehran to make concessions.

It was the first time Iran has announced the closure of the key international waterway, through which 20 per cent of the world's oil passes, since the US began threatening Iran and rushing military assets to the region.

U.S. President Donald Trump has said "regime change" in Tehran may be the best thing that can happen, while Iran's Supreme Leader Ayatollah Ali Khamenei said on Tuesday that any U.S. attempts to depose his government would fail.

Just as the talks got under way in Geneva, Iranian state media reported that parts of the strategic strait would close for a few hours due to "security precautions" while Iran's elite Revolutionary Guards conducted military drills there.

Tehran has in the past threatened to shut down the strait to commercial shipping if it is attacked, a move that would choke off a fifth of global oil flows and drive up crude prices.

Alongside Araqchi, U.S. envoy Steve Witkoff and Jared Kushner took part in the Geneva talks, which were being mediated by Oman, a source briefed on the matter told Reuters.