Iran has installed about 1,000 advanced uranium enrichment centrifuges and is set to test them, a UN nuclear report showed, a development likely to worry Western powers hoping for a change of course under the country's new president.
The International Atomic Energy Agency's (IAEA) quarterly report, the first since Hassan Rouhani won Iran's June presidential election, also said the country had started making fuel assemblies for a reactor which the West fears could yield nuclear bomb material.
Iran denies any such aim.
On the other hand, Iran's most sensitive nuclear stockpile has grown little, remaining below its arch-enemy Israel's stated “red line” that could provoke military action, since the previous IAEA report in May.
This could buy time for more negotiations with six world powers.
The IAEA report showed Iran continuing to press ahead with its disputed nuclear programme at a time when the outside world is waiting to see if Rouhani will act to ease tension with the country's Western critics.
Envoys accredited to the IAEA had cautioned against reading too much into the latest inspectors' report as it mainly covered developments before Rouhani took office on August 3, replacing Mahmoud Ahmadinejad.
Iran says its nuclear energy programme is for power generation and medical purposes only, rejecting Western allegations that it seeks the capability to make nuclear weapons.