The union representing Cathay Pacific's cabin crew said it's issuing an ultimatum to management, with members ready to act during next month's Lunar New Year holiday if concerns about pay and working conditions are not addressed.

The Cathay Pacific Airways Flight Attendants Union said it wants the airliner to address its five demands, including a minimum layover period for crew members, and increasing the number of staff on each flight.

Grace Siu, the union's external vice chairperson, said the type of action taken will depend on the airline's response but it could include a work-to-rule.

"We used to boost up our speed and maximise our level to help the company to finish everything before the time limit ends. But under work to rule, under our fatigue, we couldn’t handle that anymore," Siu said.

"So we have to follow everything under work-to-rule conditions. That might cause, obviously, the delay of the flight.”

The union said it will announce its plans ahead of time for passengers to adjust their travel plans.

In response, a Cathay Pacific spokesperson said in a statement that flight services will continue and there's no cause for concern.

“Cathay Pacific’s Inflight Services management team has communicated directly with our crew through multiple online and in-person channels. We will continue to listen to and act upon feedback from our crew,” the statement wrote, adding that union representatives have been invited to meet next month to exchange views.

The flag carrier said many of the rostering issues have been resolved, adding that layover patterns are also expected to improve gradually.

“We have benchmarked our remuneration against our peers and we are confident that we offer competitive pay for all positions, including cabin crew,” Cathay said.