(Reuters) -Air traffic control staffing issues are impacting flights for a second straight day at numerous U.S. airports as the partial government shutdown reaches its seventh day, the Federal Aviation Administration said in a notice on Tuesday.

The FAA said some flights were being delayed in Nashville and Newark airports, among others. Arriving flights were being held for up to 30 minutes at Newark due to the staffing issues.

The FAA also reported staffing issues at Atlanta Air Route Traffic Control Center and said it could reduce the number of arriving flights per hour at Chicago O'Hare.

Severe weather is also impacting flights across the country.

Some 13,000 air traffic controllers and about 50,000 Transportation Security Administration officers must still turn up for work during the government shutdown, but they are not being paid and controllers are set to receive a partial paycheck on October 14.

Transportation Secretary Sean Duffy said Monday the FAA had seen a slight increase in controllers taking sick leave and air traffic staffing has been cut by 50% in some areas since the shutdown started last week.

"If we don't have controllers we're going to make sure the air space is safe. So what we do is we'll slow traffic," Duffy said Tuesday on Fox News' "Fox and Friends."

FlightAware, a flight tracking site, said more than 2,300 flights had been delayed Tuesday, including about 200 at Nashville, or 20% of its flights.

In 2019, during a 35-day shutdown, the number of absences by controllers and Transportation Security Administration officers rose as workers missed paychecks, extending checkpoint wait times at some airports. Authorities were forced to slow air traffic in New York, which put pressure on lawmakers to quickly end the standoff.