"The Iranian oil tanker is currently heading toward the city of Iskenderun ... the Turkish tankers seem to be in their locations, their control systems are still off," the source said.
Earlier in the day, another source said that several Turkish vessels were approaching Adrian Darya near Turkey’s southern port of Mersin for unloading oil from it.
The source could not confirm whether oil had been unloaded from the tanker to Turkish vessels, but said that "given the fact that the control systems were turned off, it is likely that the unloading took place."
According to the source, the Iranian oil tanker turned off the international control system at 3:12 a.m. (00:12 GMT), while the Turkish vessels turned off their systems overnight.
Grace 1 was captured by Gibraltar's authorities, supported by UK marines, off Gibraltar’s coast on 4 July on suspicions of transporting oil to Syria in violation of EU sanctions. In mid-August, the vessel was released as Gibraltar received assurances from Iran that the tanker was not going to deliver its cargo to Syria.
The United States tried to prevent the vessel from being released after a US court ruled that the vessel, all oil on board and $995,000 in cash were subject to confiscation due to violations of a number of US laws on bank fraud and money laundering, as well as the International Emergency Economic Powers Act and a law on confiscation for terrorism-related activities.
However, the authorities of Gibraltar have rejected the United States' request to extend the detainment of the tanker, citing differences in US and European sanctions against Iran.
On Friday, the US Treasury Department said in a statement that the United States had sanctioned the tanker and its captain for transporting more than 2 million barrels of oil that would benefit Iran’s security forces.