Australia's air traffic control agency has fixed problems that delayed flights out of Sydney this morning, disrupting thousands of passengers.

Flights were held on the ground while a ''system issue'' was resolved.

Sydney Airport urged passengers to check with airlines for updated flight information.

''We appreciate your patience.''

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Airport display boards earlier today showed at least three Auckland-bound flights had been delayed.

The disruption comes as air services out of Auckland recover from the jet fuel pipeline rupture which forced airlines to cancel or re-route international flights from New Zealand and domestic services here last week.

The Australian problem has also hit as school holidays across the Tasman mean more travel by passengers who are voicing frustration about delays on social media.

Airways in this country said earlier the Auckland traffic peak may move to later in the day, depending on how long it takes to remediate the issue.

''But if it is resolved today the total number of flights won't change,'' a spokeswoman said.