"The production of uranium metal has potentially grave military implications," said the foreign ministers of Britain, France and Germany in a joint statement.

Iran had signed up to a 15-year ban on "producing or acquiring plutonium or uranium metals or their alloys" under the so-called Joint Comprehensive Plan of Action (JCPoA) signed in 2015 with world powers.

"We strongly urge Iran to halt this activity, and return to compliance with its JCPoA commitments without further delay if it is serious about preserving the deal," said the ministers.

Their call came after the International Atomic Energy Agency (IAEA) said Wednesday Iran had notified the nuclear watchdog that it was advancing research on uranium metal production, aiming to provide advanced fuel for a research reactor in Tehran.

In a response to the foreign ministers' statement, Iran's atomic energy organisation urged the IAEA to avoid creating any "misunderstanding", adding that it had not yet "presented the design information questionnaire (DIQ) of the uranium metal factory" to the watchdog.

This would be done "after carrying out the necessary preparations and... within the deadline set by law", the organisation said, in reference to a five-month deadline set by the Iranian parliament in December, mandating Tehran to ready the factory.

It said it hoped the IAEA would not cause further "misunderstanding in the future, by refraining from mentioning unnecessary details in its reports".

The landmark 2015 deal agreed between Iran and the United States, China, Russia, Britain, France and Germany to limit Tehran's nuclear programme has been largely in tatters since President Donald Trump withdrew from it in 2018 and reimposed harsh sanctions.

The Iranian government has signalled a readiness to engage with US President-elect Joe Biden, who takes office on January 20 and who has expressed willingness to return to diplomacy with Tehran.