LONDON - An Iranian tanker caught in the standoff between Tehran and the West could sail free from British territory Gibraltar on Friday, unless a last-ditch push by the United States succeeds in dragging the saga back into court.

The Grace 1 was seized by British Royal Marine commandos in darkness at the western mouth of the Mediterranean on July 4 on suspicion of violating European Union sanctions by taking oil to Syria, a close ally of Iran.

Gibraltar lifted the detention order on Thursday after it said Tehran had given written assurances that the ship would not discharge its oil in Syria. But the United States is still seeking to detain the vessel on grounds it believes it was helping Iran's Islamic Revolutionary Guard Corps.

"She is able to leave as soon as she organizes the logistics necessary in order to sail a ship of that size," Gibraltar's First Minister Fabian Picardo told BBC Radio.

"Could be today, could be tomorrow."

Asked about Washington's position, he said that would be subject to the jurisdiction of Gibraltar's Supreme Court.

"It could go back to the court absolutely."

The last-minute U.S. intervention was the latest twist in a saga that started in the early hours of July 4, when British Royal Marines abseiled onto the Grace 1 to impound the ship.

That kicked off a sequence of events that saw Tehran seize a British-flagged oil tanker in the Gulf two weeks later, heightening tension on a vital international oil shipping route.

That tanker, the Stena Impero, is still detained.

Gibraltar said it had found evidence confirming the Grace 1 was carrying its cargo - 2.1 million barrels of oil - to the Baniyas refinery in Syria. Tehran denies that. -Reuters