The US Justice Department sued a Chinese company for selling nearly a half million fake and substandard N95 respirator to US buyers in April as the COVID-19 pandemic swept the country.

In a complaint filed in federal court in Brooklyn, New York, the department said Guangdong-based King Year Packaging and Printing shipped three batches of purported N95 masks, needed to protect medical and other personnel from the coronavirus, to US buyers.

The company falsely claimed the 495,200 masks it shipped were met the N95 standard and also falsely claimed they were certified by the US National Institute for Occupational Safety and Health (NIOSH), according to the complaint.

The complaint indicated the importer of the masks paid more than $1 million for them.

"The charges alleged in this complaint show a blatant disregard for the safety of American citizens," FBI agent Douglas Korneski, who investigated the masks deal, said in a statement.

"Had it not been for the actions of the investigative team, this defendant would have put first responders, hospital employees, and other front line workers directly in harm's way with faulty equipment just to make a buck."

The Chinese company was charged with four counts of importing misbranded and substandard health products and making false to the US Food and Drug Administration.

Each charge carries a maximum fine of $500,000, or if greater, twice what the company earned in selling the masks.