Delta Air Lines plans to scale back more flights after the United States expanded travel restrictions to Britain and Ireland, it said, and Southwest Airlines was moving toward its first flight cuts as the spreading coronavirus saps demand.

Southwest, one of the few U.S. airlines still flying a full schedule, said on Saturday it was "seriously considering" cutting flights in the short term.

While airlines scramble to stem losses and protect jobs, U.S. Treasury Secretary Steven Mnuchin said on Saturday that the government would "immediately" start working with Congress to support the airline and cruise industries, both hard hit by the spiraling crisis.

U.S. Vice President Mike Pence said new restrictions on the UK and Ireland will begin Monday at midnight and will bar most non-U.S. citizens from entering the United States who have been in those countries within the last 14 days.

They do not bar flights to and from the U.S. or Americans and permanent residents from travel.

Washington first imposed restrictions on China and expanded them this week to continental Europe, prompting U.S. airlines to cut numerous flights and scramble to shore up capital and save costs.

Among cost-cutting measures, U.S. airlines are offering employees voluntary unpaid leaves of absence in an effort to better match staffing with flights.

Delta and its pilots' union, who are in contract negotiations, reached an agreement over coronavirus-related sick leave and managing overstaffing for April with partially paid schedules. United and Southwest could reach deals with their pilots soon, sources said.

Delta said Friday it would cut capacity by 40% in the next few months -- the largest reduction in its history -- and eliminate nearly all flights to continental Europe for the next 30 days. It will also park up to 300 aircraft.

United Airlines and American Airlines also announced new cuts to European service on Friday. Major U.S. airlines confirmed on Friday they had been in talks with the White House and Congress about financial assistance.

The U.S. Chamber of Commerce late Friday called for urgent action, calling on the U.S. government to "turn next to a package to assist impacted employers... No business should go bankrupt because of a temporary loss in revenue as a result of the coronavirus."

Airlines are reeling from a plunge in bookings and traffic, as the fast-spreading coronavirus pandemic prompts travel restrictions and event cancellations around the world.

U.S. passenger railroad Amtrak said on Saturday it was scaling back services due to reduced demand. Last week the company said bookings had plunged 50% since the coronavirus outbreak.