Iran has diluted its entire stock of medium-enriched uranium as required under a November deal with world powers, the UN atomic agency said in its latest report seen by AFP Monday.
Even as talks to reach a nuclear deal with Iran were extended beyond an initial July 20 deadline, the International Atomic Energy Agency (IAEA) said Tehran was standing by its international commitments.
As agreed under a so-called Joint Plan of Action reached in November, the Islamic Republic has cut half of its stock of 20-percent enriched uranium down to five-percent purity.
The rest was being converted into uranium oxide.
Tehran also refrained from enriching above the five-percent level at any of its nuclear facilities, the IAEA report said.
Iran and world powers have been trying to reach a crucial nuclear deal to alleviate international fears that Tehran is seeking a nuclear weapon.
Early Saturday, they agreed to give themselves four more months after marathon talks in Vienna.
Iran has, however, always insisted its nuclear programme was solely for peaceful purposes.
Uranium must be enriched to 90 percent to make an atomic bomb but 20-percent purity levels are just a short step from producing weapons-grade material.
Under the November interim deal, Iran and the five permanent members of the UN Security Council plus Germany agreed that Tehran would freeze certain nuclear activities for six months in return for some sanctions relief.
The West's goal is to expand the time needed for Iran to develop a nuclear weapon, giving the world ample warning of any such "breakout" push.
Talks were due to resume in the coming weeks, with November 24 as the new deadline for a lasting deal, diplomats said in Vienna.
Lead negotiator and EU foreign policy chief Catherine Ashton spoke of "tangible progress" in the talks so far but noted that "significant gaps on some core issues" remained.