The oil tanker seized by US forces on Wednesday had a track record of faking or concealing its location information, apparently to hide its activities, ship tracking data shows.

On Wednesday evening, the US confirmed that its forces seized a vessel during a helicopter-launched raid near the coast of Venezuela. BBC Verify confirmed the ship was the Skipper by matching a sign seen in footage released by the US to a reference photo supplied by TankerTrackers.com, a site which monitors oil shipments.

Data held by publicly accessible tracking sites paints an incomplete picture of the vessel’s movements, and before its seizure it hadn’t declared its position since 7 November. Maritime analytics firm Kpler also suggested that the vessel had engaged in a ship-to-ship transfer.

US Attorney General Pam Bondi described the vessel as a “crude oil tanker used to transport sanctioned oil from Venezuela and Iran”.

The US Treasury department first sanctioned the ship in 2022, when it was sailing under the name Adisa, and was accused of being part of an “international oil smuggling network”.

The Skipper has sailed under the flag of Guyana, but the government was quick to release a statement saying that the 20-year-old tanker was “falsely flying the Guyana Flag as it is not registered in Guyana”.

Experts told BBC Verify that the Skipper was likely a part of the so-called “dark fleet” – a global network of oil tankers that seek to evade oil sanctions by obscuring their ownership, identities and travel histories.

Under a UN treaty, all ships above a certain tonnage must have an onboard tracker called an Automatic Identification System (AIS). These trackers broadcast information about the ships, including their location, and can be followed on websites like MarineTraffic.

But there is an incomplete and misleading public record of the Skipper’s movements. According to MarineTraffic, the Skipper’s last known port call was at Soroosh in Iran on 9 July, where it arrived after stopping in Iraq and the UAE.

But Kpler suggests that this is part of a pattern of misleading entries by the Skipper. Analysts at the firm said the ship had previously loaded crude oil from Venezuela and Iran, while falsifying its position via its onboard tracker, a process known as spoofing.

Venezuela has some of the world’s largest reserves of oil, but exports were placed under sanctions in 2019 by the US in a bid to force the transition of power from President Nicholas Maduro’s administration, which has been widely accused of election rigging.

The firm noted that while its AIS showed the ship at Iraq’s Basrah Oil Terminal on 7 and 8 July, terminal reports showed no record of the vessel there. Instead, the Skipper loaded crude oil at Kharg Island in Iran, Kpler said.

The Skipper then sailed east, tracking data shows, where Kpler suggested it conducted a ship-to-ship transfer between 11 and 13 August. The cargo was later unloaded in China, where Kpler said it was “falsely declared”.

It returned via Iran and sailed towards the Caribbean. The Skipper last declared its position on 7 November, several miles off the coast of Guyana. Its location only reappeared on 10 December, after the US raid.

In the interim period, satellite images identified by TankerTrackers.com and confirmed by BBC Verify show that the Skipper was present in the Port of Jose in Venezuela on 18 November and not appearing on tracking sites at the time.

Since the imposition of sanctions, analysts say it has become common for ships to spoof or conceal their positions while loading oil in Venezuela.

Kpler analysts said the ship loaded “at least 1.1 million barrels of Merey crude” by 16 November at the terminal and listed Cuba as the destination.

There is also evidence that the Skipper was involved in a ship-to-ship transfer with another vessel on 7 December, just days before it was boarded by US troops. Satellite images seen by Kpler appeared to show the exchange, with one of the vessels identified by Kpler as the Skipper.

The transfer took place just off the coast of Venezuela, near the city of Barcelona. According to MarineTraffic, the Skipper had last appeared off the coast of Guyana weeks earlier.

Kpler told BBC Verify that between 28 October and 4 December, the Skipper broadcasted “manipulated” AIS signals which did not reflect its actual location.

Such sanction evading activity is not unusual for Venezuelan oil exports, Kpler said. The company said that tankers often transfer their cargo off the coast of Malaysia, before the oil is imported into China.

Former Belgian naval lieutenant and analyst Frederik Van Lokeren told BBC Verify that while such ship-to-ship transfers are not illegal or wrong, they are “extremely uncommon”. He said such activities were normally a sign of vessels trying to evade sanctions, transferring oil to ships not publicly associated with smuggling.

Mr Van Lokeren said that Venezuela’s refining capacity has been significantly degraded in recent years and is “dependent” on its allies in Iran and Russia to convert its crude oil into more commercially lucrative products.

MarineTraffic lists the beneficial owner and operator as Nigeria-based Thomarose Global Ventures Ltd and it lists the registered owner as Marshall Islands-based Triton Navigation Corp.

In 2022, the US Treasury said that Triton was being used by a sanctioned Russian oil magnate – Viktor Artemov – to facilitate a global “oil smuggling network”.

At the time, US officials said Mr Artemov used an expansive network of ships often registered obscurely to transport Iranian oil.

In its statement, the US Treasury said that Triton had “materially assisted, sponsored, or provided financial, material, or technological support for, or goods or services to or in support of, Artemov”.

BBC Verify is attempting to contact both companies for comment.