Inspectors from the International Atomic Energy Agency visited Iran's Gachin uranium mine on Wednesday for the first time in nine years, Iranian officials said.
"The inspectors expressed their satisfaction after having visited different parts of the mine," said Mohammed Amiri, an official of Iran's Atomic Energy Agency, quoted by state news agency IRNA.
He said the visit to the mine lasted five hours, while agency spokesman Behrouz Kamalvandi said earlier that it was carried out by three inspectors.
The International Atomic Energy Agency (IAEA) experts were to leave Iran in the evening, but no specific details were given of the visit, which was conducted in the absence of any media.
Their visit to the mine in southern Iran -- which had been off-limits to the IAEA since 2005 -- falls within the scope of a framework agreement which Tehran reached with the UN nuclear watchdog in November.
As part of the first phase of the deal, UN experts visited the heavy water plant at the unfinished Arak reactor on December 8, when all of the IAEA's "technical objectives" were met, the Vienna-based agency said.
The Arak reactor, still under construction, is a major source of concern for Western powers, who fear the plutonium it would produce as a by-product could provide Iran with an alternative route to an atomic bomb.
Iran agreed to freeze construction work at the site under a separate deal it reached with the major powers in November in return for some easing of crippling Western sanctions.
The six-month deal, which went into effect last week, is aimed at clearing the way for negotiations -- to open in New York next month -- on a comprehensive agreement to allay international concerns about Iran's nuclear ambitions.