Iran’s supreme leader declined US aid in fighting the coronavirus, citing a baseless conspiracy about the American government intentionally creating the virus.

“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?” Ayatollah Ali Khamenei said Sunday on state TV, according to the Associated Press. “Possibly your medicine is a way to spread the virus more.”

Khamenei claimed that the virus “is specifically built for Iran using the genetic data of Iranians which they have obtained through different means.”

It’s unclear what aid is being offered. Secretary of State Mike Pompeo said at the end of February that the United States had offered aid to Iran but did not comment on specifics.

He also claimed 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,” Khamenei continued.

Khamenei was repeating a broader conspiracy theory about the United States engineering the coronavirus as a bioweapon. Iranian state media have embraced this rumor, as have Russian media linked to the Kremlin.

The theory has also been erroneously repeated by officials in other countries’ governments, including the Philippines’ Senate President Vicente Sotto.

Chinese government spokesman Lijian Zhao also tweeted earlier this month that it “might be US army who brought the epidemic to Wuhan. Be transparent! Make public your data! US owe us an explanation!”

Last week, the peer-reviewed scientific journal Nature Medicine debunked this conspiracy theory, concluding that it was “improbable” that the coronavirus had “emerged through laboratory manipulation of a related SARS-CoV-like coronavirus.”

Khamenei’s conspiracy-mongering comes as Iran faces crippling sanctions from the US government, which has economically devastated the country by blocking it from selling oil and trading in international markets.

Iran has been ravaged by the Coronavirus, with more than 21,600 confirmed cases and 1,685 reported deaths.

According to the AP, Iran has been generally suspicious of US aid efforts. Broadly, the Trump administration has shown no interest in letting up on sanctions against Iran and vowed to apply “maximum pressure” after the United States withdrew from a nuclear deal with Iran in 2018.