Iran's supreme leader on Sunday refused U.S. assistance 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 increasing 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.

FILE — In this Tuesday, March 3, 2020 file photo released by an official website of the office of the Iranian supreme leader, Supreme Leader Ayatollah Ali Khamenei, 80, wears disposable gloves at a tree-planting ceremony in Tehran, Iran. Nine out of 10 cases of the new coronavirus in the Middle East come from the Islamic Republic. Days of denials gave the virus time to spread as the country marked the 41st anniversary of its 1979 Islamic Revolution. For most people, the virus causes only mild or moderate symptoms. For some it can cause more severe illness. (Office of the Iranian Supreme Leader via AP, File)

FILE — In this Tuesday, March 3, 2020 file photo released by an official website of the office of the Iranian supreme leader, Supreme Leader Ayatollah Ali Khamenei, 80, wears disposable gloves at a tree-planting ceremony in Tehran, Iran. Nine out of 10 cases of the new coronavirus in the Middle East come from the Islamic Republic. Days of denials gave the virus time to spread as the country marked the 41st anniversary of its 1979 Islamic Revolution. For most people, the virus causes only mild or moderate symptoms. For some it can cause more severe illness. (Office of the Iranian Supreme Leader via AP, File)

“Possibly your (offered) medicine is a way to spread the virus more,” Khamenei said. “Or if you send therapists and doctors, maybe he wants to see the effect of the poison, since it is said that part of the virus is built for Iran."

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

Khamenei made the comments in a speech in Tehran broadcast live Sunday across Iran marking Nowruz, the Persian New Year. He had called off his usual speech at Imam Reza shrine in Mashhad over the virus outbreak.

In this photo released by the office of the Iranian supreme leader, Supreme Leader Ayatollah Ali Khamenei speaks during a tree planting ceremony in Tehran, Iran, Tuesday, March 3, 2020. Iran's supreme leader put the Islamic Republic on war footing Tuesday against the new coronavirus by ordering its armed forces to assist health officials in combating the outbreak — the deadliest outside of China — that authorities say has killed 77 people. (Office of the Iranian Supreme Leader via AP)

In this photo released by the office of the Iranian supreme leader, Supreme Leader Ayatollah Ali Khamenei speaks during a tree planting ceremony in Tehran, Iran, Tuesday, March 3, 2020. Iran's supreme leader put the Islamic Republic on war footing Tuesday against the new coronavirus by ordering its armed forces to assist health officials in combating the outbreak — the deadliest outside of China — that authorities say has killed 77 people. (Office of the Iranian Supreme Leader via AP)

His comments come as Iran has over 20,600 confirmed cases of the new coronavirus amid 1,556 reported deaths.

Iran is one of the hardest-hit countries in the world by the new virus. Across the Mideast, Iran represents eight of 10 cases of the virus and those leaving the Islamic Republic have carried the virus to other countries.

Associated Press writer Aya Batrawy in Dubai, United Arab Emirates, contributed to this report.