The US Federal Aviation Administration said that Orlando International Airport later on Thursday is expected to be without certified air traffic controllers preventing landings as employee absences grow during the ongoing government shutdown.

The dramatic announcement is a stark indication of growing stress on air traffic controllers on the 30th day of the shutdown and a sign of mounting strain on US aviation.

Orlando is the 9th busiest airport in North America and serves millions of tourists and others annually in central Florida.

The FAA said it would detail updates on the impact later on Thursday at Orlando. The FAA has issued ground delay programs at Orlando, Dallas/Fort Worth and Ronald Reagan Washington National Airport because of air traffic staffing issues.

The FAA was reporting nine staffing issues at airports and centres around the country.

The FAA said flight delays were averaging more than two hours at Orlando, 90 minutes at Reagan and 21 minutes at Dallas, and it expected to delay flights at Orlando later due to staffing issues.

Tens of thousands of flights have been delayed or cancelled as staffing outages have increased dramatically during the government shutdown.

FlightAware, a flight tracking website, said nearly 5,800 flights had been delayed and 1,050 canceled on Thursday.

Earlier on Thursday, the FAA had issued a ground stop for Reagan Airport, citing issues with air traffic controller staffing.

Bad weather is also delaying flights throughout the US Northeast.

More than 13,000 air traffic controllers and 50,000 Transportation Security Administration officers are working without pay.

Transportation Secretary Sean Duffy said this week that 44 percent of delays on Sunday and 24 percent on Monday were caused by air traffic controller absences, compared to 5 percent on average before the shutdown.

The FAA is about 3,500 air traffic controllers short of targeted staffing levels and many had been working mandatory overtime and six-day weeks even before the shutdown. (Reuters)