U.N. atomic watchdog chief Rafael Grossi appealed to Iran's leadership on Tuesday to take steps to resolve longstanding issues with his agency a day before he arrives in the Iranian capital for crunch talks over its nuclear programme.

It remains unclear how President-elect Donald Trump will approach Iran once he enters office, particularly as it continues to threaten to attack Israel amid its war on Hamas in the Gaza Strip.

Iran will begin enriching uranium with thousands of advanced centrifuges at its two main nuclear facilities at Fordo and Natanz, the United Nations’