A senior White House official has accused Iran of enabling Russia's invasion of Ukraine by providing hundreds of drones to Russian forces.

National Security Council spokesperson John Kirby said on Monday that Iran has provided Russia with more than 400 drones since last August, in addition to tank rounds and artillery.

He said Russia has used most of the unmanned aerial vehicles to target critical infrastructure in Ukraine.

Kirby said Iran is getting missiles, electronics and air defense systems in return, and has a deal to buy Russian fighter jets. He said Tehran is seeking to buy billions of dollars' worth of additional military equipment from Moscow.

Kirby also said the United States will soon announce sanctions targeting the parties involved.