The Food and Drug Administration is demanding that conspiracy theorist Alex Jones stop advertising dubious dietary supplements as coronavirus treatments and threatening legal action if he doesn’t comply.

The FDA sent a letter to Jones and his website InfoWars on Thursday demanding that he stop telling the viewers of his popular internet broadcasts that they can ward off the virus with colloidal silver products sold on his website. Those videos, the FDA wrote, “misleadingly represent them as safe and/or effective for the treatment or prevention of COVID-19.”

A failure to remove those claims, the agency added, “may result in legal action seeking a Federal District Court injunction and an order may require that you pay back money to consumers.”

Jones, who is famous for fabricating conspiracy theories and marketing dubious health supplements, has been hawking supposed coronavirus-killing colloidal silver products in videos with titles like “Deep State Using Coronavirus Fear and Panic To Destroy Our Country.” In one video posted last month, he told viewers of his ”Nano Silver” supplements: “the Pentagon has come out and documented, and homeland security have said this stuff kills the whole SARS corona family, at point blank range.”

Colloidal silver is a liquid that contains tiny particles of the metal. A number of scammers and natural medicine enthusiasts have marketed it as a coronavirus treatment since the outbreak hit the U.S. There is no scientific basis for those claims.

Despite Jones’ on-air claims to the contrary, language on InfoWars’ online marketplace explicitly states that its colloidal silver products are not designed to treat the virus. “The products on this site are not intended for use in the cure, treatment, prevention or mitigation of any disease, including the novel coronavirus,” the website warns. “Any suggestion to the contrary is false and is expressly disavowed.”

Jones and InfoWars were also targeted by authorities in New York last month over his claims about the products’ ability to ward off the coronavirus. The state’s attorney general sent InfoWars a cease and desist letter demanding it stop airing dubious claims about its products’ health benefits.

Jones is among the most prominent right-wing media personalities targeted by government regulators. But others, such as Missouri televangelist Jim Bakker, have received similar warnings. The FDA wrote Bakker a letter last month demanding he stop marketing similar silver products as coronavirus treatments.