The United States on Thursday placed sanctions on an Iranian company that helped to ship drones to Russia for use in Ukraine, and warned non-Iranian firms against becoming involved in the trade.

The US Treasury said it had placed Tehran-based Safiran Airport Services on its sanctions blacklist, two months after the White House divulged intelligence that Russia was seeking Iranian unmanned aerial vehicles (UAVs) for its war on Ukraine.

The Treasury said Safiran has coordinated Russian military flights between Iran and Russia, including those that carried the UAVs, personnel and related equipment.

On August 30, a Pentagon official said Russia had begun receiving the first of what was expected to be "hundreds" of drones, and claimed, based on US intelligence, that many were already proving faulty.

"The United States is committed to strictly enforcing our sanctions against both Russia and Iran and holding accountable Iran and those supporting Russia's war of aggression against Ukraine," said Treasury Under Secretary Brian Nelson.

"Non-Iranian, non-Russian entities should also exercise great caution to avoid supporting either the development of Iranian UAVs or their transfer, or sale of any military equipment to Russia for use against Ukraine," Nelson warned in a statement.

The Treasury also placed sanctions on three Iranian companies involved in developing and producing drones and linked to the powerful Islamic Revolutionary Guard Corps.

The Paravar Pars company, Design and Manufacturing of Aircraft Engines company, and Baharestan Kish company have all participated in designing and manufacturing military UAVS in Iran, the Treasury said.

The sanctions seek to freeze any assets those designated might have under US jurisdiction and forbid any US individuals or companies -- including international banks with US operations -- to do business with them, a move aimed and blocking their access to global financial networks.