The report from the International Atomic Energy Agency comes amid growing concerns that Iran may pursue a nuclear weapon.

Iran's stock of uranium enriched to up to 60% purity, close to the roughly 90% of weapons grade, has jumped since Iran announced a dramatic acceleration in enrichment in December, a quarterly U.N. nuclear watchdog report showed on Wednesday.

Iran has sharply increased its stockpile of a critical raw material for atomic weapons, according to a confidential U.N. report.