Iran started enriching uranium up to 60% purity on Friday after an attack targeted its Natanz nuclear plant, Tehran's parliament speaker said.
Mohammad Bagher Qalibaf tweeted: "I am proud to announce that at 00:40 last night, and on the night of the pilgrimage of Sayyid al-Shuhada, young and pious Iranian scientists were able to obtain a product of 60% enriched uranium."
He added: "Congratulations to the brave people of Islamic Iran on this success."
The alleged enrichment level is now at its highest ever and comes in the wake of a sabotage at the Natanz nuclear plant last week. Iran said Israel was responsible for the attack.
Though 60% enrichment of the chemical element is is a record high for Iran, it is still below the 90% threshold required for nuclear weapons.
Friday's announcement marks a significant escalation of tensions in the Middle East and casts doubt over the chances of finding any middle ground on the Joint Comprehensive Plan of Action (JCPOA), commonly known as the Iran nuclear deal.
The 2015 accord between Iran and six nations — Germany, China, France, Russia, the United Kingdom and the United States — is currently under discussion among representatives in Vienna.
The officials are hoping to resuscitate a deal that has been on life support ever since former US President Donald Trump announced Washington's withdrawal.
jsi/rt (AP, Reuters, AFP, dpa)