"We have done nothing new and our activity is according to the regulations," said Iran's top nuclear official Mohammad Eslami.

"We were producing the same 60 percent, we didn't change anything and we didn't create any new capacity."

On Tuesday, the IAEA released a report saying Iran "increased its production of highly enriched uranium, reversing a previous output reduction from mid-2023."

Iran had increased its output of 60 percent enriched uranium to a rate of about nine kilogrammes (20 pounds) a month since the end of November, the UN watchdog said.

That is up from about three kilogrammes a month since June, and a return to the nine kilogrammes a month it was producing during the first half of 2023.

Still higher enrichment levels of around 90 percent are required for use in a nuclear weapon.

Iran has consistently denied any ambition to develop a nuclear weapons capability, insisting that its activities are entirely peaceful.

Iran appeared to have slowed its enrichment as a gesture while informal talks for a restored nuclear agreement resumed with the United States.

But animosity between the two countries has intensified in recent months, with each accusing the other of exacerbating the war between Israel and Hamas.

Iran suspended its compliance with limits on its nuclear activities set by a 2015 nuclear deal with major powers a year after then US president Donald Trump unilaterally pulled out of the agreement in 2018 and reimposed sweeping sanctions.

It has since built up its stocks of enriched uranium to 22 times the level permitted under the deal, according to a confidential IAEA report seen by AFP last month.

Eslami criticised what he called a "media frenzy" around the latest IAEA report, saying it "sought to distract public attention" from the war in Gaza.