The step was one of many mentioned in a law passed by Iran’s parliament last month in response to the killing of the country’s top nuclear scientist, which Tehran has blamed on Israel.

The move is the latest Iranian contravention of the deal, which it started violating in 2019 in response to Washington’s withdrawal from the agreement in 2018 and the reimposition of US sanctions that had been lifted under the accord.

Trump held an Oval Office meeting last month where he was ‘talked out of’ launching strikes on Iran after a UN report showed a massive increase in nuclear stockpiles in breach of the JCPOA.

Defence sources told The New York Times that Trump asked for options on a bombardment – likely to have targeted Iran’s foremost nuclear facility, Natanz.

The Fordow facility is buried underground and intelligence experts fear it could be impenetrable even to the USAF’s B-52 bombers armed with the 33,000lb ‘bunker buster.’

Before today’s announcement Iran had already upgraded its enrichment to 4.5 percent in violation of the nuclear deal which it still holds with Britain, China, France, Germany and Russia.

The deal’s main aim was to extend the time Iran would need to produce enough fissile material for a nuclear bomb, if it chose to, to at least a year from roughly two to three months. It also lifted international sanctions against Tehran.

Last month, Tehran vowed to ‘automatically’ return to its commitments under the 2015 deal if Biden lifts sanctions imposed over the past two years.

Analysts had claimed that Trump’s ‘maximum pressure’ policy has squeezed Iran so hard that it might make it easy for Biden to get them to agree to terms.

But the latest provocation could dash Democrat hopes of Biden’s triumphant return to the agreement, which they believe is the best way to stop Iran from making a nuclear bomb.

Biden’s allies argue that Trump’s aggression has only made the threat of a nuclear-armed Iran more likely.

Trump’s outgoing administration has been building a ‘wall of sanctions’ against Iran for its appalling human rights record, support for terror groups like Hezbollah and its nuclear activities.

Some believe this is an attempt to deliberately hamstring Biden, making him appear a soft-touch if he repeals the sanctions and goes to the table with Iran.

The Fordow nuclear enrichment facility, located around 80 miles south of Tehran, was never re-purposed as was promised under the JCPOA.

Iranian nuclear scientists can rapidly produce weapons-grade levels of nuclear enrichment within the deep underground corridors of the facility.

The plant is buried in a mountain range, originally under the command of the Islamic Revolutionary Guard, it is heavily fortified by a ring of steel fencing with guard towers every 80ft.