Iran is poised to reject a U.S. proposal to end a decades-old nuclear dispute, an Iranian diplomat said on Monday, dismissing it as a "non-starter" that fails to address Tehran's interests or soften Washington's stance on uranium enrichment.

Iran is currently reviewing a formal U.S. nuclear deal proposal as both sides remain deeply divided over uranium enrichment limits and sanctions relief.

Iranian, Egyptian and U.N. leaders have met to discuss Iran’s nuclear program after the U.N. nuclear watchdog agency said Iran is increasing its stockpile of uranium enriched to near weapons-grade levels.

The preliminary U.S. proposal came as a confidential U.N. report described an Iranian initiative that had multiplied Tehran’s stockpile of near-bomb-grade uranium.

Iran carried out secret nuclear activities with material not declared to the UN nuclear watchdog at three locations that have long been under investigation, the watchdog said in a wide-ranging, confidential report to member states seen by Reuters.

An IAEA report on Iran's uranium stockpile increase prompted the White House on Saturday to urge its acceptance of a proposal for a U.S.-Iran nuclear deal.

Iran's foreign ministry and the Iranian nuclear agency rejected the report, calling it "politically motivated" in a joint statement.

Iran criticized a new report by the UN nuclear watchdog accusing it of nuclear violations, claiming the agency is motivated by politics and reiterating it isn’t seeking atomic weapons.

A new Austrian intelligence reports says Iran is continuing with its nuclear program as the U.S. and Iran hold indirect talks over dismantling Tehran’s atomic weapons program.

Iranian, Egyptian and U.N. leaders met in Cairo on Monday to discuss Iran's nuclear program after a report from the U.N. nuclear watchdog agency said that Iran is further increasing its stockpile of uranium enriched to near weapons-grade levels.