GIBRALTAR >> An Iranian supertanker hauling $130 million worth of light crude oil that the U.S. suspects to be tied to a sanctioned organization has lifted its anchor and begun moving away from Gibraltar, marine traffic monitoring data showed late today.

The trail left by GPS data on Marinetraffic.com, a vessel tracking service, showed the Iran-flagged Adrian Darya 1, previously known as Grace 1, moving shortly before midnight. The tanker slowly steered southeast toward a narrow stretch of international waters separating Morocco and the southern tip of the Iberian Peninsula.

The vessel had been detained for a month in the British overseas territory for allegedly attempting to breach European Union sanctions on Syria. Gibraltar authorities rejected an eleventh-hour attempt by the United States’ to reseize the oil tanker today, arguing that EU regulations are less strict than U.S. sanctions on Iran.

The vessel’s next destination was not immediately known.

An on-duty officer at the Port Authority of Gibraltar declined to comment on the ship’s moves and deferred questions to the government. The Gibraltar government press office did not immediately respond to messages seeking comment.

Iran’s ambassador to Britain, Hamid Baeidinejad, had earlier announced on Twitter that the ship was expected to leave tonight.

The tanker’s release comes amid a growing confrontation between Iran and the West after President Donald Trump pulled Washington out of Tehran’s nuclear deal with world powers over a year ago.

Shortly after the tanker’s detention in early July near Gibraltar — a British overseas territory — Iran seized the British-flagged oil tanker Stena Impero, which remains held by the Islamic country. Analysts had said the Iranian ship’s release by Gibraltar could mean that the Stena Impero goes free.

Gibraltar’s government said today it was allowing the Iranian tanker’s release because “The EU sanctions regime against Iran – which is applicable in Gibraltar – is much narrower than that applicable in the US.”

In a last-ditch effort to stop the release, the U.S. unsealed a warrant Friday to seize the vessel and its cargo of 2.1 million barrels of light crude oil, citing violations of U.S. sanctions as well as money laundering and terrorism statutes.

U.S. officials told reporters that the oil aboard the ship was worth some $130 million and that it was destined for a designated terror organization.

The unsealed court documents argued that Iran’s Islamic Revolutionary Guard Corps are the ship’s true owners through a network of front companies.

Authorities in Gibraltar said today that, unlike in the U.S., the Iran’s Revolutionary Guard is not designated a terrorist organization under EU, U.K. or Gibraltar law.

The Iranian ship was detained while sailing under a Panamanian flag with the name Grace 1. As of today, it had been renamed the Adrian Darya 1 and had hoisted an Iranian flag. Workers were seen painting the new name on the side of the ship Saturday.

Iran has not disclosed the Adrian Darya 1’s intended destination and has denied it was ever headed for Syria.

The chief minister of Gibraltar, Fabian Picardo, said he had been assured in writing by the Iranian government that the tanker wouldn’t unload its cargo in Syria.

The Astralship shipping agency in Gibraltar, which has been hired to handle paperwork and arrange logistics for the Adrian Darya 1, had told The Associated Press that a new crew of Indian and Ukrainian nationals had been expected to replace the sailors on board.

Messages seeking comment from the Iranian Embassy in London were not immediately returned.