Iran has 4,000 working nuclear centrifuges, an official said in remarks published on Friday, in line with a number verified by the UN atomic watchdog but lower than a figure cited by President Mahmoud Ahmadinejad.
Iran says it is installing centrifuges to enrich uranium so it can make fuel for nuclear power plants. But the West accuses Tehran of seeking to master technology so it can enrich uranium to much higher levels for use in nuclear warheads.
Ahmadinejad said last month Iran had more than 5,000 centrifuges running but the International Atomic Energy Agency (IAEA) later said he appeared to have overstated the number by at least 1,000.
"There are currently close to 4,000 centrifuges active at Natanz enrichment facility. ... Another 3,000 centrifuges are being installed," Deputy Foreign Minister Alireza Sheikh Attar told state television, the official IRNA news agency reported.
World powers have offered Iran a package of trade, nuclear and other incentives to halt its sensitive nuclear work, but Tehran has repeatedly said it will not halt enrichment plans, the part of the program that most worries Western capitals.
The United States and its Western allies have said they are pushing for more UN sanctions, after three sets of penalties have been imposed since 2006.
Analysts say Washington may now find it more difficult to secure UN Security Council backing for another sanctions resolution because of the crisis with Russia, a veto-wielding council member, about Georgia.