– Sweeping U.S. sanctions are hampering Iranian efforts to import medicine and other medical supplies to confront one of the largest coronavirus outbreaks in the world, health workers and sanctions experts say.

The broad U.S. restrictions on Iran's banking system and the embargo on its oil exports have limited Tehran's ability to finance and purchase essential items from abroad, including drugs as well as the raw materials and equipment needed to manufacture medicines domestically.

The Trump administration has also reduced the number of licenses it grants to companies for certain medical exports to Iran, according to quarterly reports from the Office of Foreign Assets Control, or OFAC, the enforcement agency of the U.S. Treasury Department. The list of items requiring special authorization includes oxygen generators, full-face mask respirators and thermal imaging equipment, all of which are needed to treat patients and keep medical workers safe, doctors say.

The tough measures are part of a U.S. "maximum pressure campaign" against Iran, adopted by the Trump administration after it unilaterally withdrew from the 2015 nuclear deal Iran had signed with world powers.

Iranian medical workers and global public health experts say it is not possible to determine exactly how much U.S. sanctions have impacted Iran's capacity to fight the virus — which has infected more than 35,000 Iranians, killed at least 2,500 and spawned outbreaks in other countries. But they say it is clear that the Iranian health care system is being deprived of equipment necessary to save lives and prevent wider infection.

"There are a lot of shortages now. … [Hospitals] do not have enough diagnostic kits or good quality scanners, and there is also a shortage of masks," said Nouradin Pirmoazen, a thoracic surgeon and former lawmaker in Iran.

Pirmoazen, who now lives in Los Angeles, said that he is in regular contact with former colleagues and students at the Masih Daneshvari Hospital in Tehran, part of Iran's National Research Institute of Tuberculosis and Lung Diseases.

"Medical staff who want a specific type of medicine or equipment are having difficulty transferring money outside of Iran due to the sanctions," he said, adding that doctors and nurses at Masih Daneshvari have been overwhelmed by the crisis.

An employee of a major pharmaceutical company in Iran who spoke on the condition of anonymity said that "the sanctions have definitely made the import and production processes longer and more expensive."

"Some suppliers are afraid and not willing to work with us anymore," she said. "The sanctions have reduced Iran's capacity to control the outbreak."

According to the World Health Organization, the toll from the novel coronavirus in Iran is likely five times higher than official figures show. Earlier this month, the Washington Post obtained reporting data from a network of hospitals in Tehran, including Masih Daneshvari, that suggested the epidemic was far more widespread than the government had acknowledged.

Iranian leaders have come under fire for what critics say was a botched response to the outbreak, including initially refusing to quarantine affected areas or close religious shrines, measures that likely allowed the deadly pathogen to spread.

On Thursday, the Interior Ministry announced new restrictions on travel between provinces and ordered all nonessential shops to close.

"The reality is that the government refused to admit that it had a problem," said Amir Afkhami, an associate professor and global health expert at George Washington University. "There was a lack of transparency and officials took what were clearly inadequate precautionary measures."

The U.N. has called for an "urgent" re-evaluation of sanctions against countries grappling with the pandemic.