U.S. Secretary of State John Kerry arrives in Vienna to meet with his Iranian and EU counterparts in a push to reach a final agreement on Iran's controversial nuclear program by a November 24 deadline.
A senior U.S. official said a deal is still possible by late next month and there were no talks now about extending the deadline.
The negotiations are centered on curbing Iran's atomic activity, which Tehran says is peaceful but the West fears may be aimed at developing a nuclear weapons capability.
With the clock ticking, Western officials say there are still important differences between the sides, especially over the future scope of Iran's production of enriched uranium, which has both civilian and military applications.
