The US has disrupted a multimillion-dollar shipment of crude oil sent by Iran's Islamic Revolutionary Guard Corps in breach of sanctions, the Justice Department said on Friday.
More than 980,000 barrels of oil were also seized by US authorities.
The announcement concludes a months-long episode involving Empire Navigation, a Greek shipping company that on Thursday admitted to smuggling Iranian crude oil that was the subject of sanctions on the Suez Rajan tanker.
The company has been sentenced to three years probation and ordered to pay a $2.4 million fine.
The tanker was previously suspected of transferring sanctioned Iranian oil to a client in Asia.
“This is the first-ever criminal resolution involving a company that violated sanctions by facilitating the illicit sale and transport of Iranian oil,” the Justice Department said in a statement.
The cargo is now subject of a civil forfeiture action. The US complaint alleges that the oil is subject to forfeiture based on terrorism and money-laundering statutes.
Washington's complaint accuses several entities affiliated with the IRGC and its Quds Force of attempting to covertly sell and transport Iranian oil abroad. Those involved are also alleged to have tried to disguise the ship's origin.
The IRGC and Quds Force attempted to disguise the vessel's origin using methods such as ship-to-ship transfers, a false identification system report and falsified documents.
The complaint alleges “that profits from oil sales support the IRGC’s full range of malign activities, including the proliferation of weapons of mass destruction and their means of delivery, support for terrorism and both domestic and international human rights abuses”, the Justice Department said.
The IRGC and Quds Force are designated as foreign terrorist organisations by the US.
For months, the Suez Rajan was docked in the South China Sea near Singapore.
As part of a plea deal with the US in late April, Empire Navigation agreed to transport the oil to the US, the Justice Department said. The company incurred expenses associated with the voyage.
The episode has escalated tensions between the US and Iran. Tehran has since attempted to seize two tankers near the Strait of Hormuz, through which 20 per cent of the world's oil passes.
California-based company Oaktree Capital Management sold the vessel to Empire Navigation in May.