WASHINGTON, Nov 7 (Reuters) -

The U.S. Federal Aviation Administration said on Friday it

was delaying flights at eight airports including in Atlanta, San

Francisco, Houston, Washington and Newark, citing widespread air

traffic staffing issues as controllers have not been paid during

the government shutdown.

The FAA said it has staffing shortages at 10 locations across

the country, which could potentially result in delays at more

airports.

The agency has separately required airlines to cancel 4% of

flights at 40 high-volume airports to address air traffic

control staffing -- or more than 700 flights in total.

Under FAA ground delay programs, flights are being delayed

by an average of 83 minutes at Reagan Washington National, 66

minutes at San Francisco, 52 minutes at Newark, 47 minutes at

Austin, and 80 minutes at Houston Bush.

More than 2,300 flights had been delayed as of 12:45 p.m. EST,

according to Flightwire, a flight tracking site. Some airlines

have expressed concern that controllers, who have not been paid

during the shutdown, might feel emboldened not to show up for

work because of the flight reductions.

The 38-day shutdown, the longest in U.S. history, has

forced 13,000 air traffic controllers and 50,000 Transportation

Security Administration agents to work without pay.

In an interview Friday, Transportation Secretary Sean Duffy

said he had asked the controllers union to reach out to

controllers to ask them to come to work.

"I need them to come to work," Duffy said. "This is not

about you now having a 'get-out-of-jail-free' to not come to

work."

The FAA said this week that 20% to 40% of controllers daily

were not showing up for work.

On Oct. 31, the FAA said nearly half of the 30 busiest U.S.

airports faced shortages of air traffic controllers, leading to

more than 6,200 flights being delayed and 500 canceled, in the

single worst day since the shutdown began. In New York 80% of

air traffic controllers were absent.