UN nuclear watchdog chief Rafael Grossi will fly to Tehran this weekend for talks that may ease a standoff between Iran and the West just as it risks escalating negotiations on reviving the Iran nuclear deal, diplomats said on Saturday. Three diplomats who follow the International Atomic Energy Agency (IAEA) closely said Grossis trip before next weeks meeting of the IAEAs 35-nation board of governors was confirmed. One said Grossi would arrive in Tehran early on Sunday and meet the head of the Atomic Energy Organization of Iran.