The US has warned Greece that it risks facing American sanctions if it gives safe harbor to Iran’s Grace 1 oil tanker, in the latest standoff between the US and EU over the ship’s fate.

Axar.az reports citing telegraph that the Iranian oil tanker left Gibraltar over the weekend after a month in British detention and is now heading towards the Greek port of Kalamata.

"We have made clear that anyone who touches it, anyone who supports it, anyone who allows a ship to dock is at risk of receiving sanctions from the United States,” said Mike Pompeo, the US secretary of state.

The Grace 1, now renamed the Adrian Darya 1, has not officially confirmed it is heading to Greece and the Greek government said it was monitoring the situation.

"The vessel is cruising at low speed and there is still no formal announcement that it will arrive at Kalamata. The Merchant Marine Ministry is monitoring the matter along with Greece's Foreign Ministry," a Greek Shipping Ministry spokesman said.