The Federal Aviation Administration said it is reviewing some 450 cases of passengers behaving badly on airline flights and has opened 20 formal enforcement cases as flight attendants continue to grapple with people refusing to comply with orders to wear masks aboard airplanes.

In light of those figures, the agency said Monday that it would extend a “zero-tolerance” policy for bad behavior as long as a federal mask mandate for transportation remains in force. The FAA has the power to levy fines and make criminal referrals against passengers who violate safety rules.

“The policy directs our safety inspectors and attorneys to take strong enforcement action against any passenger who disrupts or threatens the safety of a flight, with penalties ranging from fines to jail time,” FAA administrator Steve Dickson said in a statement. “The number of cases we’re seeing is still far too high, and it tells us urgent action continues to be required.”

The initial order went into force Jan. 13, a week after airlines reported a wave of disruptive behavior linked to the storming of the U.S. Capitol by supporters of President Donald Trump. It was due to expire at the end of March.

The FAA said airlines had reported more than 500 incidents to the agency since late December, mostly involving passengers refusing to wear masks.

On Friday, the agency announced that it was seeking a $14,500 fine against a man accused of refusing to wear a mask on a JetBlue flight from New York to the Dominican Republican on Dec. 23. The man ignored warnings from flight attendants that he had to follow the rules and the captain ultimately declared an emergency and returned to New York, the FAA said.

Sara Nelson, president of the Association of Flight Attendants, a major union, said the FAA’s policy had served as an effective deterrent against bad behavior. The union had called for it to be extended.

“People need clear instructions on safety,” Nelson said in a statement. “The patchwork, politically skewed discussion around masks has created confusion and conflict. We don’t have time for failure to comply with the federal mask mandate. On an airplane, that behavior puts everyone at risk and we can’t stand for that.”

In the past, the FAA has only rarely used its enforcement powers, initiating some 1,300 cases in the past decade.

Measures to limit the spread of the coronavirus by travelers have been significantly tightened under the Biden administration.

In January, the Centers for Disease Control and Prevention issued a sweeping mandate requiring masks on planes and other forms of transportation. The Transportation Security Administration said that violating those rules could come with fines of more than $1,000.