The U.K.’s biggest airlines have asked the government for economic support as new travel restrictions threaten to upend the peak Christmas season for a second year.

The government’s latest moves, which include reintroducing expensive hotel quarantines and travel bans for passengers arriving from southern Africa, are putting more pressure on airlines that were counting on Christmas travel to start to offset huge losses accumulated during the pandemic.

“As leaders of U.K. airlines, we are deeply concerned about the haphazard and disproportionate approach by government to travel restrictions following the emergence of the omicron variant,” the chief executives of carriers including British Airways and Ryanair Holdings Plc wrote in a letter to Prime Minister Boris Johnson.

In the letter, the airlines asked for bespoke economic support packages and the removal of emergency testing requirements for fully vaccinated passengers.

The airline industry said that ticket sales covered just 30% of winter holiday capacity after the new restrictions undermined customer sentiment.