Disrupted air travel along the heavily populated US East Coast was resuming normal operations on Saturday after the US Federal Aviation Administration said it had fixed an automation problem at an air traffic center that led to hundreds of flight cancellations.

The FAA said an air traffic center in Leesburg, Virginia was thought to be the cause of the issue which cancelled more than 440 flights for hours and caused hundreds of other flights to be delayed during the busy August travel season.

The FAA said it was working with carriers to resume normal service and that the problem "has nothing to do with an accident or hacking."

The biggest bottlenecks were at airports around the nation's capital, where thousands of passengers were left waiting for planes delayed for hours or had to rearrange travel plans because their flights were cancelled.

More than 440 flights were cancelled at airports along the US East Coast on Saturday, according to flightaware.com, a service that tracks global air service.

By comparison, large and severe weather systems in the United States can cause more than 1,000 cancellations in a day.

Tens of thousands of passengers were affected as flights up and down the Atlantic Coast were cancelled or delayed.

"The FAA is continuing its root cause analysis to determine what caused the problem and is working closely with the airlines to minimize impacts to travellers," it said in a statement. – Reuters