Jetstar flights have been delayed on one of the busiest travel days of the year due to a computer problem.

Jetstar said flights were not operating on Saturday morning due to a problem with its IT systems.

The airline said flight plans could not be updated and no flights could take off until the issue was resolved.

The systems are now back online but flight delays of 60 to 90 minutes are expected across the airline’s Australian and New Zealand networks.

Dozens of passengers took to social media to vent their frustrations with the airline.

“60-90 minutes?! Three and a half hours I’ve been waiting and now my flight is cancelled. Won’t be on a flight for another three hours,” wrote Monica Tietjens.

“Why today Jetstar? Why why why?” wrote Elisha Adele.

It is understood Qantas flights, which use a different system, were not affected.