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.

A classified International Atomic Energy Agency report found Iran, since February, produced 300 pounds of uranium enriched to 60%, a step away from weapons-grade.

A senior Iranian official told CNN the new nuclear deal proposal presented to Tehran in recent days is “incoherent and disjointed,” as sources familiar with the progress of the talks said the momentum behind negotiations to secure a new deal appears to be collapsing.

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.

Iran lashes out at Austria after a report claims Tehran has an advanced nuclear weapons program, sparking diplomatic tensions and calls for explanations.

Saudi Arabia's defence minister delivered a blunt message to Iranian officials in Tehran last month: take President Donald Trump's offer to negotiate a nuclear agreement seriously because it presents a way to avoid the risk of war with Israel.