Hundreds of passengers have been stranded at Sydney Airport after more than 50 flights were cancelled today due to an unexpected air traffic controller shortage. 

Airservices Australia was forced to reduce the number of aircraft movements due to poor weather this afternoon but delays worsened when a staff member called in sick with late notice.

As a result, 26 departures and 32 arrivals have been cancelled.

Airlines were left scrambling to notify passengers, many of whom were told of the delays moments before boarding.

Airservices Australia said a replacement air traffic controller has since been called in but not before flights were impacted.

“We are working on all measures to minimise further impact, including accommodating additional flights wherever safe,” an Airservices Australia spokesperson said.

“Airservices apologises to passengers affected by delays and cancellations, and we are disappointed that this has occurred so soon after our strong performance over the Christmas period, when ground delays were at record lows across the network.”

Virgin Airlines said it was communicating with impacted passengers and trying to get them onto next available services.

It is understood most of the passengers will have to fly tomorrow.

Meanwhile, commuters are facing their own delays after industrial action has caused 90 per cent of the train services to be cancelled this afternoon.