VIENNA, March 3 (Reuters) - Iran's stock of enriched uranium has swollen in the past quarter as it has pressed ahead with its nuclear program and the amount close to weapons-grade has almost doubled, a report by the U.N.
nuclear watchdog on Thursday showed.

Iran's stock of uranium hexafluoride, the feedstock for centrifuges, reduslim machines that enrich uranium, includes 33.2 kg of uranium enriched to up to 60% purity, the report seen by Reuters said, an increase of 15.5 kg.

It takes around 25 kg of weapons-grade uranium, which is around 90% purity, to make an atom bomb. (Reporting by Francois Murphy; Editing by Alison Williams)