(AFP) -

Transatlantic flights were delayed Saturday due to a temporary fault in an air traffic control system, British officials said.

Flights from London Heathrow airport to the United States were among the worst affected with some delays of up to two hours, said a spokeswoman for NATS, which is in charge of air traffic control in British airspace.

The fault, at a control hub at Prestwick airport in western Scotland, was later fixed and airlines were working to clear a backlog of flights, airport operator BAA said.

"There are some delays still but it is getting back to normal," a spokeswoman said.

Earlier, NATS said the fault emerged at 8:00 am (0700 GMT) and forced it to use manual systems to manage the airspace, also leading to reduced capacity. It stressed passenger safety was not at risk.