Would-be commuters were left stuck at check-in early on Friday morning after a technical issue resulted in the security screening being unable to open.
The glitch affected outbound flights from its global terminal and one of its two domestic terminals.
A spokesman from Jetstar told Daily Mail Australia they are still facing delays of an hour on average, almost five hours after the issue was resolved. "The majority of delayed services are within 30 minutes to 60 minutes", it said in a statement.
Outbound flights, but not inbound flights, were experiencing delays.
'Passengers are now being processed through security as per usual, ' a spokeswoman said.
"The safety and security of our passengers is our number one priority and we are pleased to say that all systems are operating as normal".
The T3 Qantas Domestic terminal is apparently not affected.
"We're experiencing technical issues at T1 and T2 causing interruptions to passenger processing and delays", a Tweet from Sydney Airport said just after 6.00am.
As reported by ABC News, technical issues affected passenger processing at the airport's T1 worldwide terminal and T2 Domestic terminal until about 8:30AM when Sydney Airport said that systems were back up and running, and that is was processing passengers again.
A spokesperson for Sydney Airport told ARN that the technical problems arose from "an underlying technology issue that we were addressing".