Officials said that they were monitoring reports of drone activity in the Newark area. (File)

Air traffic at Newark Liberty International Airport was temporarily halted early Monday evening after two drones were spotted in the area.

Gregory Martin, a spokesman for the Federal Aviation Administration, said the drones were seen flying near Teterboro Airport around 5 p.m. Teterboro is a general aviation airport located about 20 miles north of Newark International. As a precaution, arriving flights at Newark were temporarily held. He said the ground stop was put into place as a precautionary measure.

Drones can cause severe damage to aircraft and distract pilots. The drones in the Newark incident were flying at 3,500 feet, officials said.

Passengers reported that some flights were forced to circle the airport before being cleared to land.

Martin said there is a ground stop in place at other airports on flights headed for Newark until the backlog of arrivals has landed at the airport.

Officials at United Airlines said that they were monitoring reports of drone activity in the Newark area, but that the effect on its flight operations had been minimal.

"We are working closely with the airport and the FAA to return our operations to normal as quickly as possible," the airline said.

Earlier this month, officials were forced to halt flights at London's Heathrow Airport after reports of drone activity. In December, officials at Gatwick Airport suspended flights at Gatwick Airport twice in the same week because of drone activity. Two people were arrested in connection with those incidents.

When a drone collided with a passenger plane over Quebec City last year, the plane landed safely. But officials said a different point of impact could have been devastating.