Greece says it won't assist an Iranian supertanker sought by the U.S. that's in the Mediterranean Sea, believed headed for a Greek port.

Deputy Foreign Minister Miltiadis Varvitsiotis says Greece is under pressure from U.S. authorities, which claim the Iran-flagged Adrian Darya 1 is tied to a sanctioned organization.

Varvitsiotis says the tanker is too big for any Greek port and can't legally unload its $130 million worth of light crude at EU refineries.

Crew members of the Grace 1 super tanker remove the name of ship in the British territory of Gibraltar, Saturday, Aug. 17, 2019. The shipping agent for an Iranian supertanker caught in a diplomatic standoff says the vessel is ready to depart Gibraltar in "24 to 48 hours," despite a last-minute effort by the United States to seize it again. (AP PhotoMarcos Moreno)

Crew members of the Grace 1 super tanker remove the name of ship in the British territory of Gibraltar, Saturday, Aug. 17, 2019. The shipping agent for an Iranian supertanker caught in a diplomatic standoff says the vessel is ready to depart Gibraltar in "24 to 48 hours," despite a last-minute effort by the United States to seize it again. (AP PhotoMarcos Moreno)

The ship left Gibraltar on Sunday after being held up for a month for allegedly attempting to breach EU sanctions on Syria. Gibraltar said Iran provided assurances the tanker wouldn't unload its cargo in Syria.

Varvitsiotis told private Antenna TV Wednesday Athens sent "a very clear message" it will not facilitate the crude's transportation to Syria.