Iran plans to install hundreds more advanced uranium-enriching centrifuges at an underground plant in breach of its deal with major powers, a UN nuclear watchdog report showed on Friday, a move that will raise pressure on US President-elect Joe Biden.

The confidential International Atomic Energy Agency (IAEA) report obtained by Reuters said Iran plans to install three more cascades, or clusters, of advanced IR-2m centrifuges in the underground plant at Natanz, which was apparently built to withstand aerial bombardment...