The UN nuclear watchdog chief is likely to defend a deal with Iran to the agency’s 144-nation assembly on Monday as Western critics call for harsh sanctions on Tehran and talk of war as a ”worst-case” option.

Iran’s pact with the International Atomic Energy Agency to clarify past nuclear research left untouched its programme to enrich uranium, seen by the West as a disguised bid for bombs, and split the IAEA’s 35-nation board of governors last week.