Flights in and out of Newark were delayed for about an hour. (Representational image)

The busy Newark airport serving the New York area was briefly closed Saturday after a United Airlines flight experienced multiple flat tires upon landing and skidded partly off the runway, the airline and Federal Aviation Administration said.

No major injuries were reported in the incident at Newark Liberty International Airport in New Jersey, just across the Hudson River from New York.

The FAA said United Airlines flight 627, arriving from Denver, landed at 1 pm (1700 GMT) before skidding off the left side of a runway, with its main landing gear getting stuck in a grassy area.

The plane with 166 passengers aboard had multiple flat tires upon landing and "became disabled," United spokesman Robert Einhorn said in a statement.

Flights in and out of Newark were delayed for about an hour while passengers deplaned and the aircraft was moved, the FAA said, adding that its investigators were en route to the airport.

Passengers with minor injuries refused medical attention, Einhorn said, though paramedics were at the scene as a precaution.

The airport had at first tweeted about an unspecified "emergency," but later announced the resumption of flights.

"Delays are expected to continue," it added.