Passengers were told to expect delays when travelling in and out of Sydney Airport today. (ABC News: Rhiannon Soliman-Marron)
Passengers have faced delays at Sydney Airport as Airservices Australia managed roster constraints in the air traffic control tower.
There were more than 150 flight delays on Saturday morning.
Sydney Airport encouraged passengers to check in with their airline for the latest information.
Sydney Airport has warned of delays to flights on Saturday, with the chief executive of Australia's airline industry group saying more than 150 have been impacted.
It is believed the network across both international and domestic terminals was affected.
There were about 95 delays across the Qantas network, including to about 25 QantasLink services.
Virgin Australia also experienced delays to some flights operating to and from Sydney.
Virgin Australia flights were impacted. (ABC News: John Gunn)
In a statement, a Sydney Airport spokesperson said reduced air traffic movement rates were being managed by Airservices Australia.
It said the problem was "expected to impact flight schedules across the network and may result in delays".
CEO of industry group Airlines for Australia and New Zealand, Stephen Beckett, said thousands of passengers were affected as a result of Airservices Australia's "operational challenges".
"We understand that they are again struggling to have enough people rostered on in the air traffic control tower to keep the air service operating efficiently," he said.
"The advice we've received is that both international and domestic flights are being impacted.
There were about 95 delays across the Qantas network. (ABC News: John Gunn)