New York City is in danger of running out of swabs for Covid-19 tests and is urging medical providers to continue testing only patients who are gravely ill, AP quoted the city health department as saying in a memo to health care providers.

"As the swab supply continues to decline, there is a real possibility hospitals will completely run out," the April 11 health alert said. "At this time, providers are reminded to only test hospitalised patients in order to preserve resources that are needed to diagnose and appropriately manage patients with more severe illness."

The warning came amid repeated pleas from New York City and state officials for the federal government to provide widespread testing in order to move to a containment phase in the coronavirus outbreak.