Tehran issues warning against U.N. snapback sanctions amid concerns over its nuclear program, while expert warns that enforcing the U.N. mechanism could prompt Iran to exit non-proliferation treaty.

The "snapback mechanism" is a process that would reimpose U.N. sanctions on Tehran under a 2015 nuclear deal that lifted the measures in return for restrictions on Iran's nuclear programme.

A U.N. official says the pace and scale of Afghans returning from Iran are overwhelming already fragile support systems.

More than half a million Afghans have been expelled from Iran in the 16 days since the conflict with Israel ended, according to the United Nations, in what may be one of the largest forced movements of population this decade.

IAEA chief Rafael Grossi confirms Iran has nuclear material but says he is not seeing "any tangible proof that there's a program, or a plan ... to manufacture a nuclear weapon."

The United Nations atomic watchdog said its remaining inspectors in Iran have left the country, deepening the blackout over Tehran’s nuclear program just weeks after it was targeted by massive