WASHINGTON (REUTERS) - A total of 80 unruly plane passengers have been referred to the FBI for potential criminal prosecution, the Federal Aviation Administration (FAA) said on Wednesday (Feb 16), as onboard disruptions rose sharply in 2021, many over Covid-19 mask requirements.

The US Justice Department has pledged to take a tough line and some airlines and labor unions have called for a "no-fly" list that would ban passengers with a record of disruptions.

The increase in cases is tied to pandemic restrictions that have prompted friction on planes.

The FAA, which said last year it had referred 37 passengers to the FBI for review, said about 4,600 of the 6,400 unruly passenger reports it has received since the start of 2021 through Feb 15 involve passengers not wearing a mask as required.

Delta Air Lines chief executive Ed Bastian this month asked US Attorney-General Merrick Garland to place passengers convicted of on-board disruptions on a national "no-fly" list that would bar them from future travel on any commercial airline.

Bastian said the action would "help prevent future incidents and serve as a strong symbol of the consequences of not complying with crew member instructions on commercial aircraft."

Delta has placed nearly 1,900 people on its "no-fly" list for refusing to comply with masking requirements and submitted more than 900 banned names to the Transportation Security Administration to pursue civil penalties, Bastian said.

Sara Nelson, president of the Association of Flight Attendants-CWA representing nearly 50,000 flight attendants at 17 airlines, said her union urges "the creation of a centralised list of passengers who may not fly for a period of time after being fined or convicted of a serious incident."

The Justice Department said it is giving priority to investigations and prosecutions of people who commit crimes that threaten the safety of passengers, flight crews and flight attendants.

Airlines have been holding discussions for months with federal agencies on the possibility of a nationwide "no-fly"list but there is no indication of any imminent action.

A group of eight Republican senators on Monday wrote to Garland, criticising Delta's "no-fly" proposal. They said it would "result in a severe restriction on the ability of citizens to fully exercise their constitutional right to engage in interstate transportation."