DUBAI, United Arab Emirates — Iran’s supreme leader refused U.S. assistance Sunday to fight the new coronavirus, citing an unfounded conspiracy theory that the virus could be man-made by America.

Ayatollah Ali Khamenei’s comments come as Iran faces crushing U.S. sanctions blocking the country from selling its crude oil and accessing international financial markets.

But while Iranian civilian officials in recent days have increasingly criticized those sanctions, 80-year-old Khamenei instead chose to traffic in the same conspiracy theory increasingly used by Chinese officials about the new virus to deflect blame for the pandemic.

“I do not know how real this accusation is but when it exists, who in their right mind would trust you to bring them medication?” Khamenei said. “Possibly your medicine is a way to spread the virus more.”

He also alleged without offering any evidence that the virus “is specifically built for Iran using the genetic data of Iranians which they have obtained through different means.”

“You might send people as doctors and therapists, maybe they would want to come here and see the effect of the poison they have produced in person,” he said.

There is no scientific proof offered anywhere in the world to support Khamenei’s comments.