An increase in sick leave among air traffic controllers delayed flights at several major East Coast airports on Friday, the Federal Aviation Administration said.

Flights at New York's LaGuardia Airport, Newark Liberty International Airport and Philadelphia International Airport were delayed on Day 35 of the partial government shutdown. The FAA had briefly halted flights into LaGuardia and some arriving flights were delayed almost an hour and a half, the agency said.

Flights out of Philadelphia International Airport were delayed up to an hour and 15 minutes, and 45 minutes at Newark, the FAA said.

"The President has been briefed and we are monitoring the ongoing delays at some airports," said White House spokeswoman Sarah Sanders. "We are in regular contact with officials at the Department of Transportation and the FAA."

Airline executives and aviation workers have warned that the partial government shutdown could roil air travel. Some 420,000 federal workers, including Transportation Security Administration screeners and air traffic controllers, have been deemed essential and told to go to work even though they aren't receiving regular pay in the shutdown.

"We have experienced a slight increase in sick leave at two facilities," the FAA said. "We've mitigated the impact by augmenting staffing, rerouting traffic, and increasing spacing between aircraft when needed. The results have been minimal impacts to efficiency while maintaining consistent levels of safety in the national airspace system."

The FAA said the two stations affected by the shortages of workers were in Jacksonville, Florida and in Washington, D.C.

On Thursday, an FAA spokesman said the agency had seen "no unusual increased absenteeism and there are no operational disruptions due to staffing" because of the government shutdown.

A spike in the absences of Transportation Security Administration screeners has led to longer lines at some of the country's busiest airports earlier this month.

Correction: Headlines for this story were revised to correct that the disruptions stemmed from a shortage of air traffic control workers.

This story is developing. Please check back for updates.