The comment by Mohammad Bagher Qalibaf, quoted by state television, did not elaborate on the amount Iran planned to enrich.

However, it is likely to raise tensions even as Iran negotiates with world powers in Vienna over a way to allow the US back into a 2015 nuclear deal and lift the crushing economic sanctions it faces.

Former US president Donald Trump pulled out of the deal in 2018.

The Iranian enrichment announcement also marks a significant escalation after the sabotage that damaged centrifuges, an attack this past weekend suspected of having been carried out by Israel.

While Israel has yet to claim it, the country is widely suspected of having carried out the still-unexplained sabotage at Natanz, Iran's main enrichment site.

"The will of the Iranian nation is a miracle-maker and it will defuse any conspiracy," state television quoted Qalibaf as saying. He said the enrichment began just after midnight on Friday.

The head of the Atomic Energy Organisation of Iran, the country's civilian nuclear arm, later acknowledged the move to 60 per cent, according to state TV.

While 60 per cent is higher than any level Iran previously enriched uranium, it is still lower than weapons-grade levels of 90 per cent.

Iran had been enriching up to 20 per cent - even that was a short technical step to weapons grade. The deal limited Iran's enrichment to 3.67 per cent.

The International Atomic Energy Agency, which monitors Iran's nuclear program, did not immediately respond to a request for comment. Earlier this week, it sent its inspectors to Natanz and confirmed Iran was preparing to begin 60 per cent enrichment at an above-ground facility at the site.

The heightened enrichment could inspire a further response from Israel amid a long-running shadow war between the nations.

Israeli Prime Minister Benjamin Netanyahu has vowed never to allow Tehran to obtain a nuclear weapon and his country has twice preemptively bombed Mideast nations to stop their atomic programs.

Australian Associated Press