IRAN announced today that it will enrich uranium at levels higher than the limit agreed in a deteriorating 2015 nuclear development treaty.

Nuclear agency spokesman Behrouz Kamalvandi said that enrichment above the previously agreed 3.67 per cent would begin “within hours” in response to US President Donald Trump’s abandonment of the agreement and imposition of harsh sanctions on Tehran.

Initially the enrichment will be increased to 5 per cent — far short of the 90 per cent level required for nuclear weapons. Iran has always insisted that its nuclear programme is for civil energy purposes only.

Deputy Foreign Minister Abbas Araghchi, who is in charge of nuclear negotiations, said that Iran would keep reducing its commitments every 60 days until other signatories move to get the deal back on track.

French President Emmanuel Macron said at the weekend that he was doing all he could to resume dialogue following last week’s seizure of an Iranian oil tanker by Britain, reportedly on US instructions.

Iran has said it is open to returning to talks and would be happy for all original signatories to the deal, including the US, to take part on condition that the US lift its sanctions.

But the country’s communist Tudeh Party warned that breaching the deal’s terms would be “seized on by the US and its allies in Israel, Saudi Arabia and the United Arab Emirates” and could be used as a pretext for an attack.

Tudeh international secretary Navid Shomali said: “While it is Trump’s government that has heightened the tensions by unilaterally withdrawing from the [nuclear deal] and massively increasing the pressures on Iran with a crippling sanctions regime, Araghchi’s announcement is a sign of further escalation.

“Iran’s national economy has already been hollowed out after three decades of neoliberal economic restructuring which has turned it into a rentier, import-based and dollar-based economy relying on the export of crude oil.

“Any provocation could be seized upon by the US,” whose military threats have created “an ominously similar situation to that created during the lead-up to regime change in Iraq,” Mr Shomali told the Morning Star.

Israeli Prime Minister Benjamin Netanyahu said that sanctions on Iran should be tightened in response to the news.