Hossein Simorgh, spokesman of Iran's Atomic Energy Organisation's public relations department, said "no new centrifuges have been installed in Natanz", referring to the nuclear facility in central Iran, the official Islamic Republic News Agency reported late on Saturday.
Earlier in the day, Alaeddin Boroujerdi, a legislator, said Iran was currently installing the 3,000 centrifuges, underlining that the country would continue to develop its disputed nuclear programme despite UN sanctions.
Contradictions
It was not immediately clear why the two officials made contradicting statements. Iranian officials have in recent weeks said the country was moving towards large-scale enrichment involving 3,000 centrifuges, which spin uranium gas into enriched material.
Mohammad Ali Hosseini, Iran's foreign ministry spokesman, refused to elaborate on the discrepancy on Sunday, saying only that the contradicting remarks were a "technical matter".
He said: "Let the organisation elaborate on it at a convenient time."
Ivanov visit
Further, Hosseini said Igor Ivanov, Russia's national security adviser, arrived in Tehran on Sunday for talks with top leaders, including Mahmoud Ahmadinejad, Iran's president, and Ali Larijani, the country's nuclear negotiator.
Diplomats have said inspectors from the UN watchdog, the International Atomic Energy Agency (IAEA), had concluded Iran was ready to start installing the centrifuges.
But they said timing the installation was likely to be a political decision.
UN resolution
The UN Security Council last month voted unanimously in favour of imposing limited sanctions on Iran after it ignored earlier demands to halt enrichment.
Iran faces the prospect of additional sanctions unless it stops enrichment by the end of a 60-day period that ends next month.
Enriched uranium is used to fuel nuclear reactors and to make nuclear weapons, and large scale use of centrifuges makes it possible to produce more enriched uranium in a shorter period.
Moderate politicians in Iran, particularly critics of Mahmoud Ahmadinejad, the president, have been counselling caution and possibly even suspending enrichment, until now a step opposed by Iran.
Ahmadinejad has been blamed by critics for exacerbating the standoff with the West, although the final say in nuclear policy and other matters of state lies with Ayatollah Ali Khamenei, Iran's highest authority.