Iran has announced plans to install advanced uranium enrichment machines in what would be a technological leap allowing it to significantly speed production of material that the West fears could be put to developing nuclear weapons.
An International Atomic Energy Agency said on Thursday that Tehran has advised it will introduce new centrifuges to its main enrichment plant near Natanz.
The move will increase concerns in the West and Israel about Iran's nuclear ambitions, which Tehran says are entirely peaceful.
The IAEA said Iran informed it in a letter dated 23 January that "centrifuge machines type IR2m will be used in Unit A-22" at the Fuel Enrichment Plant (FEP) at Natanz.
In a reply dated 29 January, the International Atomic Energy Agency asked for more information on the announcement.