Iran deal could stumble on sensitive nuclear monitoring

Iran's Foreign Minister Javad Zarif addresses during a joint statement with EU foreign policy chief Federica Mogherini in Lausanne April 2, 2015. Iran and world powers reached a framework on curbing Iran's nuclear programme at marathon talks in Switzerland on Thursday that will allow further negotiations towards a final agreement. REUTERS/Ruben Sprich

UNITED NATIONS (Reuters) - Beefing up international monitoring of Iran's nuclear work could become the biggest stumbling block to a final accord between Tehran and major powers, despite a preliminary deal reached last week.

As part of that deal, Iran and the powers agreed that United Nations inspectors would have "enhanced" access to remaining nuclear activity in Iran, where they already monitor key sites.