US Federal officials say they are pursuing civil penalties against two more passengers for interfering with airline crews, the latest in a surge of such cases in recent months. The Federal Aviation Administration said it is continuing to take a zero-tolerance stance against unruly passengers.

The most recent cases involve a passenger who refused to wear a face mask, which is required by federal regulation, and another who cursed flight attendants and the captain after boarding a plane.

The Federal Aviation Administration says it has received 1,300 complaints from airlines about disruptive passengers this year and has announced proposed civil penalties – some topping US $30,000 – against more than a dozen passengers in recent weeks. The passengers can protest the penalties.

The agency said Monday it will seek a US $10,500 fine against a passenger on a JetBlue Airways flight from Fort Lauderdale, Florida, to Los Angeles in December. The FAA said the man repeatedly ignored orders to wear a mask, then coughed and blew his nose into a blanket.

The FAA proposed a US $9,000 fine against a passenger who boarded a JetBlue flight from Los Angeles to Newark, New Jersey, in March. The man slammed overhead bins and shouted profanities at flight attendants and the captain before law enforcement escorted him out of the terminal, the FAA said.

The new cases came just three days after the FAA announced potential fines against four other passengers. None of the individuals have been identified.

Under its zero-tolerance policy announced in January, the FAA says it no longer warns or counsels unruly passengers, it jumps straight to enforcement action. The FAA has power to levy civil penalties but is letting law enforcement decide whether to seek criminal charges against passengers.

The FAA crackdown began around the time supporters of Donald Trump created disturbances on several flights to and from Washington. It was to remain in effect until late March, but the agency extended it when the Transportation Security Administration extended its requirement that passengers wear face masks through Sept. 13.

The FAA says it started enforcement action against more than 1,300 passengers during the past 10 years.

US airlines, which imposed their own face-mask requirements before the government did, have temporarily banned at least 3,000 people for refusing to cover their faces.