U.S. expected to keep oil embargo even if Iran nuclear deal struck

VIENNA (Reuters) - A unilateral U.S. oil embargo on Iran is expected to remain in place even if a long-term nuclear agreement between Tehran and six world powers is reached that includes an easing of international sanctions, a U.S. official said on Thursday.

The embargo pre-dates the decade-long nuclear dispute with Iran. Washington cut off diplomatic ties with Tehran during a hostage crisis shortly following the 1979 Islamic Revolution and began imposing sanctions around the same time.

"The American domestic oil embargo is expected to remain in place even if a comprehensive agreement is reached," the U.S. official told Reuters on condition of anonymity.

Western diplomats say U.S. companies would be unhappy about being left out if European Union and U.N. sanctions are lifted, allowing non-U.S. firms to resume business with the Islamic Republic. Iranian officials say they would have no problem with American oil companies returning to Iran.

The U.S. official spoke after Iran and the six powers - Britain, China, France, Germany, Russia and the United States - agreed on an agenda and schedule for talks aimed at ending the dispute over Tehran's nuclear ambitions.

Earlier, a senior U.S. official said the United States would like to see sanctions lifted, but that cannot happen until an agreement on Iran's nuclear project is reached. Another U.S. official said those remarks referred only to sanctions imposed after the dispute over the nuclear program broke out in 2002.

(Additional reporting by Fredrik Dahl and Parisa Hafezi; Editing by Larry King)