Government air traffic controller Airservices Australia said in a statement that it had experienced a "technical issue which is affecting arriving and departing aircraft at Sydney Airport".
Flights were briefly prevented from taking off and landing at Sydney Airport's domestic terminal on Monday during the peak morning travel period due to a technical fault with an air traffic control system.
The issue had been resolved, the airport said on its official Twitter feed, but officials said travellers faced delays as a result of the outage.
Government air traffic controller Airservices Australia said in a statement that it had experienced a "technical issue which is affecting arriving and departing aircraft at Sydney Airport".
ASA gave no further details but boards at the airport listed flights as "delayed due to ATC radar failure."
"Our technicians are currently working to rectify the situation," ASA said.
Qantas Airways Ltd, the country's biggest carrier, said in a statement posted on its Website that there were "significant delays at Sydney Airport affecting all airlines" without giving more detail.
A spokesman later said in an email that "things are starting to flow again but still some delays".
Virgin Australia Holdings Ltd, the country's No. 2 carrier, was also affected.
"Due to an issue with Air Traffic Control at Sydney Airport earlier today, some Virgin Australia flights may be impacted. We are working to have all guests on their way as quickly and safely as possible," it said in a statement.
Hundreds of passengers were expected to face delays as the technical glitch hit during the Monday morning peak travel window and one of the first days of a two-week school vacation period.
Sydney Airport said in a message posted to its official Twitter feed that the "issue has now been resolved".
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