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.

The head of the United Nations nuclear watchdog warned Tuesday that "the margins for manoeuvre are beginning to shrink" on Iran's nuclear programme ahead of an important trip to Tehran."The Iranian administration must understand that the international situation is becoming increasingly tense and that the margins to manoeuvre are beginning to shrink,