US authorities have warned that the pace of air travel in the United States could soon slow dramatically as thousands of flights are canceled or delayed and travelers face widespread chaos due to the government shutdown.

The administration of US President Donald Trump has ordered airlines to reduce the number of their flights at 40 airports to ease the pressure on air traffic controllers who are working without pay due to the ongoing six-week federal shutdown.

The government shutdown that began on October 1 has halted the salaries of tens of thousands of air traffic controllers, airport security personnel, and others.

Federal agencies across the United States have been shut down since Congress failed to approve funding after September 30. Approximately 1.4 million federal employees, from air traffic controllers to national park rangers, remain on administrative leave or working without pay.

Transportation Secretary Sean Duffy told Fox News on Sunday, as the Thanksgiving holiday approaches in two weeks, that"air travel will slow down considerably" as "everyone wants to travel to see their families."

The same official pointed out that “a very small number of air traffic controllers will be reporting for duty, which means few flights will be landing and taking off,” adding: “We will face great disruption (and) many angry Americans.”

In a statement to CNN, Duffy said that “things will get worse” as people seek to travel to meet their families during the holidays, and noted that many will not be able to travel “because there won’t be many flights” if the lockdown does not end.