The ship was photographed off the coast of Syria on Friday and is believed to have been carrying 2.1 million barrels of Iranian crude oil. The UK’s Foreign Office has described the reports of the ship as “deeply troubling”. The UK also said if Iran were to backtrack on their assurances they would be in “violation of international norms and a morally bankrupt course of action”.
The US has said they would impose sanctions on any buyer of the oil.
It is thought the ship turned off its transponder in the Mediterranean Sea before travelling to Syria.
The tanker sent its last signal giving it location between Cyprus and Syria sailing north last Monday.
The US has been trying to seize the vessel as part of its sanctions targeting the Iranian energy industry.
US Treasury official Sigal Mandelker said: “We will continue to put pressure on Iran and as President Trump said there will be no waivers of any kind for Iran’s oil.”
Iran’s foreign ministry has said they they have sold oil without identifying to which country.
The US has warned any country that if they assist the ship, they would see this as support for a terrorist organisation.
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“Tehran thinks it’s more important to fund the murderous Assad regime than provide for its own people.
“We can’t talk, but Iran’s not getting any sanctions relief until it stops lying and spreading terror.”
Tensions between the US and Iran have been high since Donald Trump pulled out of the Iran nuclear deal.
The deal involved Iran being sanctioned if the country was found to be building weapons.
Since this Trump has re-imposed sanctions, which have crippled the Iranian economy.
France has proposed offering Iran $15 billion in credit lines if Tehran comes back and complies with the 2015 nuclear deal.