The sisters, Jessica and Lisa Origliasso, have labelled the incident on the Brisbane-bound Qantas flight on Sunday morning "incredibly intimidating and confusing".

Qantas says two passengers refused to follow the cabin crew's instructions after boarding flight QF516 and were "offloaded" before the plane left Sydney.

The Australian Federal Police told AAP officers came on board amid an argument between the passenger and staff before the women agreed to disembark, with no further issues.

But the duo have denied accounts of the incident, which include claims of a cabin baggage dispute.

"The details reported are false and in conflict with video recorded during the event and witness accounts from the flight," they said on Instagram.

"The incident was escalated without explanation why from the cabin staff. We co-operated with all requests from authorities and exited the aircraft."

The Veronicas, who caught a later flight to Brisbane, added they were pursuing legal action over the incident and subsequent media reports.

Police say they're still looking into the incident.

Australian Associated Press