A crew member raises the Iranian flag on Iranian oil tanker Adrian Darya 1, previously named Grace 1. Photo: Reuters/Jon Nazca.

An Iranian tanker at the center of a confrontation between Washington and Tehran has switched destinations and is now heading to Turkey instead of southern Greece, data from real-time ship tracking website MarineTraffic showed on Saturday.

The Adrian Darya, formerly called Grace 1, was released from detention off Gibraltar after a five-week standoff over whether it was carrying Iranian oil to Syria in violation of European Union sanctions in mid-August.

The United States, which says the tanker is controlled by the Iranian Revolutionary Guards, deemed a terrorist group by Washington, has told countries in the region not to assist it.

Previous data had shown that the vessel, which is fully laden with oil, was heading to the port of Kalamata in Southern Greece. But new data from MarineTraffic on Saturday showed the vessel will now sail past Greece through the Mediterranean and dock at the southern Turkish port of Mersin on Aug. 31.

Greece had said it would not offer any facilities to the tanker.