MONACO—A leading Saudi prince demanded a place for his country at talks with Iran, assailing the Obama administration for working behind Riyadh's back and panning other recent U.S. steps in the Middle East.

Prince Turki al-Faisal, an Arab royal and a brother of Foreign Minister Saud al-Faisal, said Saudi Arabia and other Gulf states were stunned by the secret American-Iranian diplomacy that led to the breakthrough deal between Iran and other world powers last month.

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