Late yesterday, the Brisbane Airport Corporation confirmed the pair were mistakenly allowed out of a ‘red zone’ into the ‘green zone’ that at the time was being used by up to 390 passengers bound for New Zealand.

The news alarmed authorities and would-be travellers on both sides of the Tasman, and this morning Premier Annastacia Palaszczuk confirmed one of the travellers had since tested positive for COVID-19.

It is unclear what impact the bubble breach will have on travel arrangements between Australia and New Zealand. There are meetings of National Cabinet, health ministers and health officials today, with updates expected this afternoon.

Chief Health Officer Dr Jeannette Young has declared the international terminal a venue of concern, asking anyone who was there between 9.45am and midday on Thursday to monitor their symptoms and get tested immediately if they feel unwell.

“Staff who came into contact with this case have been placed into quarantine,” Young said.

“We have advised the NZ Ministry of Health of the latest results and they are taking their own protection measures.”

The pair had arrived from Port Moresby in Papua New Guinea, where the rate of COVID-19 infection has forced Australia to take additional precautions, at around 9.30am.

Instead of staying in the ‘red zone,’ they were allowed to visit retail outlets in the ‘green zone’ where they remained for almost two hours.

In that time, three flights departed for New Zealand, however the corporation believed only a handful of passengers were even in the vicinity of the pair.

“BAC is conducting a thorough investigation and unreservedly apologises for this human error,” a spokeswoman said.

Queensland Health said the pair had reportedly tested negative to COVID-19 before departing Port Moresby. They were tested again in Brisbane yesterday – one returned a negative result but the other was equivocal – and further testing was being conducted overnight.

The traveller with the equivocal result then tested positive, a development announced by Palaszczuk in a tweet. Two other new cases were detected in hotel quarantine.

Queensland Health had earlier downplayed the risk to other travellers, saying the pair wore masks and socially distanced while at the airport.

The three flights affected are Air New Zealand NZ202 from Brisbane to Christchurch, Air New Zealand NZ146 from Brisbane to Auckland, and Qantas QF135 from Brisbane to Christchurch.