American Federal officials said Friday they are seeking civil fines of US $15,000 and $7,500 against two airline passengers accused of assaulting flight attendants for telling them to wear face masks. The Federal Aviation Administration said the proposed penalties stem from separate incidents in August.

The FAA, which doesn’t have authority to file criminal charges, did not name the passengers.

The larger fine involves a passenger on an Allegiant Air flight from Clearwater, Florida, to Mascoutah, Illinois. The FAA said the passenger repeatedly screamed obscenities at a flight attendant, then hit him and grabbed his phone while he was telling the captain about the passenger’s behaviour. The plane made an unscheduled landing to deal with the situation.

The second incident occurred on a SkyWest Airlines flight from Atlanta to Chicago. The FAA said that passenger removed their face covering, bothered other passengers, and grabbed a female flight attendant’s buttock.

Despite requests by airline unions, the FAA has declined to make wearing a face covering a federal rule. The FAA said civil penalties can be imposed against people who assault or threaten others on a flight. Federal law provides for criminal fines and jail terms for passengers who interfere with an airline crew member’s duties, but those must be filed by law enforcement agencies.

All leading US airlines require passengers to wear coverings, with exceptions generally made for children under 2.

US airlines say they have banned more than 1,000 passengers for failing to wear masks.

Both passengers have 30 days to respond to enforcement letters from the FAA.