Thousands of travellers have had their holiday plans ruined after scores of Christmas Eve flights were cancelled without notice.

Jetstar, Qantas and Virgin abruptly axed dozens of flights across Australia on Friday.

There are reports up to 80 flights were cancelled from Sydney alone – including 35 flights between Sydney and Melbourne, 10 to Brisbane and another four to the Gold Coast.

Up to a dozen flights were also cancelled from Melbourne – although many also took off as scheduled on Friday.

Many of the mass cancellations were due to a lack of ground staff, with scores of workers forced into COVID isolation after being identified as close contacts, particularly in Sydney.

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In a statement, Jetstar said a “large number” of its frontline workers had been ordered to test and isolate in Sydney and Melbourne, forcing some “late adjustments”. The airline said it was working to accommodate passengers on other flights.

“We appreciate the frustration this causes, especially as customers are travelling for Christmas, and sincerely apologise for the impact these changes are having on travel plans,” the spokesperson said.

Virgin Australia said it was “working around the clock” to get travellers to their destinations.

“We apologise to any guest impacted by changes to our schedule and we are working around the clock to ensure our guests get to their final destination as planned,” a Virgin Australia spokesperson said.

“Guests are encouraged to visit the Virgin Australia website to check the status of their flight prior to travel. All impacted guests are automatically being moved onto alternative services as close to the original departure time as possible.

“Virgin Australia is operating hundreds of services today with little to no impact on scheduled departure or arrival times.”

Some travellers complained of lengthy delays getting through to the airline’s service number.

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Across NSW in particular, many businesses – especially in hospitality – have reported struggling with a lack of staff due to the state’s spike in COVID cases.

On Thursday, NSW Premier Dominic Perrottet confirmed up to 1500 health workers were in isolation due to the spread of the virus.

There were another 5612 cases in NSW on Friday, down from Thursday’s record high. Victoria had another 2095, up slightly from Thursday.

There were also new record 24-hour case tallies in South Australia (688), Queensland (589), the ACT (102) and Tasmania (27).

The cancellation of flights came after people travelling for Christmas had already faced long delays to meet interstate COVID test requirements.

Queensland, South Australia, Tasmania and the Northern Territory all require negative PCR tests for arrivals from interstate hotspots.

That, combined with continued high case numbers, has swamped testing sites, especially in NSW and Victoria.

NSW chief health officer Dr Kerry Chant said being notified about a case from a QR code check-in was not necessarily a reason for a PCR test.

“What we are stressing is that is a prompt, a reminder to monitor for symptoms. So please get tested if you’re unwell, but don’t get tested unless you are feeling unwell,” Dr Chant said on Friday.