Iran plans to inform the UN nuclear watchdog in Vienna over its start of a process to increase the country's uranium enrichment capacity.
"In a letter that will be handed over to the International Atomic Energy Agency ... Iran will announce that the process of increasing the capacity to produce ... UF6 (uranium hexafluoride) ... will start on Tuesday," Iran's Atomic Energy Organisation spokesman Behrouz Kamalvandi told ISNA news agency.
He said Iran had the capacity to accelerate production of centrifuges, which are used to enrich uranium. The UF6 is a feedstock for centrifuges.
Iran's ultimate authority Supreme Leader Ayatollah Ali Khamenei on Monday said he had ordered preparations to increase uranium enrichment capacity if a 2015 nuclear deal with world powers falls apart after the US withdrawal from it last month.
"The leader (Khamenei) meant that we should accelerate some process ... linked to our nuclear work capacity to move forward faster, in case needed," Kamalvandi said.
European signatories of the accord back the deal but have concerns over Iran's ballistic missile program and its influence in the Middle East.
Iran says the two issues are non-negotiable.
