The Atomic Energy Organization of Iran (AEOI) said the speed of low-grade uranium enrichment had been increased four times since Tehran announced in May that it would stop complying with parts of the nuclear agreement, the Joint Comprehensive Plan of Action (JCPOA), after the US unilaterally withdrew from the deal.
"We have quadrupled the rate of enrichment and even increased it more recently so that in 10 days it will bypass the 300 kg limit," AEAI spokesman Behrouz Kamalvandi said in a televised statement from the Arak Nuclear Plant.
In two months Iran would also surpass the 130 tonnes-limit of heavy water the historic deal allows it to store, Iranian news agency Mehr reported.
Iranian President Hassan Rouhani said in May his country would scale back its compliance with the 2015 accord, which saw Tehran trade in much of its nuclear programme for a slight alleviation of international economic sanctions.
Rouhani's announcement came a year after US President Donald Trump withdrew from the pact, which was also signed by China, Russia, the UK, France and Germany.
By pulling out of the nuclear deal, the Trump administration paved the way for issuing fresh sanctions against Tehran, targeting Iran's banking and oil sectors.
Rouhani initially issued a 60-day moratorium for the remaining signatories to offer counter-measures to the US actions with regards to upholding the deal. He had warned if the remaining parties failed to come up with a compromise, Iran would "stop respecting the limit of 3.67 per cent low-enriched uranium".
The AEOI spokesman, according to Efe news, said Iran had two theories as to why the European nations in the pact were unable to offer solutions: "The first, they don't want to uphold their commitment, and, the second, they don't have the ability to confront the US."
"They should adopt measures as soon as possible because if we start to advance (with the nuclear programme) it will be hard to return to the original situation," he said.
Tensions between Washington and Tehran have spiralled in recent months. The US has increased its military presence in the region and has blamed Iran for a series of alleged sabotage attacks against oil tankers near the Strait of Hormuz.
( With inputs from IANS )