Aug. 19 (UPI) -- Iranian officials warned the United States Monday to leave a supertanker detained by Britain last month alone, now that it's been freed and heading toward Greece.
The tanker, the Adrian Darya 1, left Gibraltar late Sunday and plotted a course for the Mediterranean. The vessel, formerly known as the Grace 1, was captured by British forces July 4 and U.S. officials suspect it planned to ship oil to Syria, in violation of U.S. and European Union sanctions.
The United States requested to seize control of the ship, but the Gibraltar Supreme Court declined -- arguing the U.S. sanctions are stricter than the EU's.
Iranian foreign ministry spokesman Abbas Mousavi told reporters Monday any U.S. attempt to seize the tanker would "constitute a threat against free shipping." He warned against undertaking "wrongheaded action" and pledged "adverse consequences" if the United States attempts to interfere.
U.S. officials say the tanker is controlled by Iran's Islamic Revolutionary Guard Corps through front companies.
The U.S. Justice Department unsuccessfully attempted to intervene last week when the Gibraltar high court was set to release the tanker. It was released to Tehran after officials promised it wouldn't violate European Union sanctions by shipping oil to Syria.
The U.S. government said the ship's the crude oil was subject to forfeiture based on violations of the International Emergency Economic Powers Act.
The vessel is heading for Greece and is expected to arrive there next week.