In his apology, Atlas claimed he was unaware RT was a registered foreign agent.

RT is owned by Russian state-owned news agency RIA Novosti and subsidiary RT America is registered with the US Justice Department as an agent of the Russian government. The Kremlin uses RT to spread English-language propaganda to American audiences, and was part of Russia's election meddling in 2016, according to a 2017 report from the US Office of the Director of National Intelligence.

Twitter labeled a video from the Russian-state controlled broadcaster RT as election misinformation on Thursday. YouTube videos posted by RT carry the disclaimer: "RT is funded in whole or in part by the Russian government."

Earlier this year, an internal intelligence bulletin issued by the Department of Homeland Security said Russia was amplifying disinformation about mail-in voting as part of a broader effort "to undermine public trust in the electoral process."

In its filing to register as a foreign agent, RT's production company in the United States said its role is to "inform, not influence" and "are not aimed to primarily benefit any foreign government or political party."

A senior White House official told CNN Sunday that Atlas did not have clearance from the Trump administration for his interview with RT. The official said Atlas "did it on his own without approval by the White House." Senior aides raised concerns internally after Atlas appeared on RT, the source said. RT said the interview was done from the White House property.

Dubious claims

In the 27-minute interview on Saturday, Atlas made a series of dubious claims. For example, Atlas misrepresented the effectiveness of masks, suggested that lockdowns kill people and discouraged testing of asymptomatic people. He also dismissed forecasts from the Institute for Health Metrics and Evaluation at the University of Washington School of Medicine that forecasts 399,000 coronavirus deaths in the US by February 1 under current conditions.

"The IHME model is really sort -- it's absurd to start looking at this model at this point," Atlas said. "At this point in time anybody who's even focusing on models has not learned from the past."

In July, the IHME model predicted 208,255 Americans would have died from coronavirus by Nov. 1. In fact, according to Johns Hopkins University, 230,566 people have died as of Nov. 1.

Atlas is a radiologist and who has no expertise in infectious diseases or epidemiology.

Atlas' history of controversy

In October, Twitter removed a tweet from Atlas that sought to undermine the importance of wearing a face mask, because Atlas' tweet was in violation of the its Covid-19 Misleading Information Policy, a spokesman for the company told CNN. The tweet said, "Masks work? NO" followed by a series of falsehoods about the science behind the effectiveness of masks in combating the pandemic.

He also encouraged officials to limit Covid-19 testing mainly to people experiencing symptoms. And on August 31, Atlas and Florida Governor Ron DeSantis urged public health officials in several Florida cities to focus less on universal testing and more on opening the economy and schools.

Trump has relied on Atlas for advice on handling the coronavirus. But Dr. Anthony Fauci, the country's leading infectious disease expert, has criticized Atlas, a neuroradiologist and Trump's hand-picked coronavirus adviser, for his lack of expertise.

"I have real problems with that guy," Fauci said in an interview with the Washington Post Friday. "He's a smart guy who's talking about things that I believe he doesn't have any real insight or knowledge or experience in. He keeps talking about things that when you dissect it out and parse it out, it doesn't make any sense."