UN nuclear watchdog has confirmed that Iran has begun construction of an underground centrifuge assembly plant.

Rafael Grossi, director-general of the International Atomic Energy Agency (IAEA), told the Associated Press in an interview that Iran also continues to stockpile large amounts of low-enriched uranium but has no plans to develop weapons.

A nuclear plant at Iran’s Natanz nuclear site that exploded in July this year, has been prompting U.S. experts to say it exploded at a new centrifuge plant.

Analysts say the Natanz blasts have so far shown no signs of construction in Iran’s central province of Isfahan.

On the other hand, Iran’s mission to the United Nations has not commented on the request to immediately respond.