GIBRALTAR: An Iranian supertanker with $130 million worth of light crude oil that the US suspects is tied to a sanctioned organization has left Gibraltar and is heading east into the Mediterranean Sea, with its next destination reported to be Greece. Ship tracking service MarineTraffic said on Monday that the Iran-flagged Adrian Darya 1, previously named Grace 1, has set course for Kalamata, Greece, with an estimated arrival on August 25. It wasn't immediately clear why the tanker would be heading there or whether the destination could change. The vessel left Gibraltar late on Sunday after having been detained for a month in the British overseas territory for allegedly attempting to breach European Union sanctions on Syria. Gibraltar authorities rejected attempts by the US to seize the oil tanker. (UPDATED) Iranian tanker sought by US heads to unknown destination GIBRALTAR: An Iranian supertanker hauling $130 million worth of light crude oil that the US suspects to be tied to a sanctioned organisation lifted its anchor and begun moving away from Gibraltar late on Sunday. 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 went south before steering eastwards toward a narrow stretch of international waters separating Morocco and the southern tip of the Iberian Peninsula. Iran's ambassador to Britain, Hamid Baeidinejad, confirmed in a post on Twitter that the oil tanker was headed to international waters. Questions to the embassy about where it was going were not immediately returned. 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 on Sunday, arguing that EU regulations are less strict than US sanctions on Iran. 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 republic. Analysts had said the Iranian ship's release by Gibraltar could mean that the Stena Impero goes free. Gibraltar's government said Sunday 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 US unsealed a warrant Friday to seize the vessel and its cargo of 2.1 million barrels of light crude oil, citing violations of US sanctions as well as money laundering and terrorism statutes. US 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 is the ship's true owners through a network of front companies. Authorities in Gibraltar said Sunday that, unlike in the US, Iran's Revolutionary Guard is not designated a terrorist organization under EU, UK or Gibraltar law. The Iranian ship was detained while sailing under a Panamanian flag with the name Grace 1. As of Sunday, 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 the 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.