At least a dozen returnees have left New Zealand immediately after completing managed isolation, raising questions about whether the MIQ system was being abused.

This week, as investigations began into how three people linked to the Pullman Hotel managed isolation facility became infected with Covid-19, Australian authorities advised a dozen Pullman departees had touched down in Sydney. Three reportedly travelled on to Hong Kong.

Their flying visits to New Zealand came as thousands of Kiwis overseas faced months-long waits to return home.

Among them was Trev Ponting, 46, who has brain cancer and has been given just months to live. His family's application for an emergency spot in managed isolation was initially denied on Friday, before being reviewed and approved yesterday.

National’s health spokesperson Chris Bishop said he was surprised that 12 people finished managed isolation and left the country immediately.

“Within the bounds of respect for privacy, we do need more information about why this happened and how widespread it is,” Bishop said.

“MIQ spots are limited, and I think people are bemused at people being cooped up for 14 days and then immediately leaving again.”

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But managed isolation and quarantine does not keep records of people’s movements once they leave facilities, and was unaware of how many people may have since left the country, a spokesperson said.

When detailed questions were put to Covid-19 Response Minister Chris Hipkins, he told Stuff there was no evidence to suggest people were using New Zealand MIQ as a “back door” for further travel.

“However we are aware of people leaving New Zealand following their stay in MIQ,” Hipkins said.

“While we do not know whether their motivations differ to those outlined in their MIQ booking application, we would take a dim view to anyone looking to isolate in New Zealand with the intention of ongoing travel.”

Before last Sunday’s news of a community Covid-19 case in Northland, those travelling to most parts of Australia did not have to quarantine when they touched down across the Tasman.

However, the quarantine-free travel bubble to Australia was suspended last Monday, with the Australian Government set to make a decision today on whether to reinstate the arrangement.

Those who do leave New Zealand within three months of arriving are expected to pay for the cost of their stay in managed isolation.

No new community cases were announced yesterday, but there was one new case in managed isolation.