Iran nuclear talks may be extended as U.S. sees 'big gaps'

U.S. Secretary of State John Kerry (L), Iranian Foreign Minister Javad Zarif (R) and EU envoy Catherine Ashton pose for photographers before a meeting in Vienna November 22, 2014. REUTERS/Leonhard Foeger

VIENNA (Reuters) - World powers and Iran struggled on Saturday to overcome the differences preventing them from ending a 12-year standoff over Tehran's atomic ambitions, raising the prospect of another extension to the high-stakes talks.

U.S. Secretary of State John Kerry said "big gaps" remained with two days to go before a self-imposed Nov. 24 deadline for an accord, despite signs of some headway. A European source said the chance of a final deal by Monday was "very small".