Singapore's Changi Airport banned all transiting visitors only hours ago while flights transiting through Dubai are dwindling.

Mercy flights are being considered as the government and tourism industry work together to support those left stranded in the wake of Covid-19.

Tourism Industry Aotearoa chief executive Chris Roberts said transit hubs were vital for many visitors travelling here.

"Clearly everyone coming from Europe has to transit through somewhere. There are some quite significant markets that have to take two flights to get to New Zealand and those two flight options are rapidly disappearing. Only point-to-point flights are being allowed and that means people can't get home," Roberts said.

He estimated tens of thousands of visitors are stuck in limbo.

While there was no shortage of accommodation available, Roberts said the question was who footed the bill.

"Some of these visitors won't be in any position to pay for a hotel for say the next month when they were expecting to be only here for a couple of weeks," he said.

"We'll have to consider the government picking up the tab to look after some of these stranded visitors."

Tourism Export Council chief executive Lynda Keene agreed, saying visitors would need support.

"The New Zealand government needs to provide some form of duty of care so a decision needs to be made about what they will do to house and accommodate the visitors," Keene said.

Foreign nationals departing Aotearoa and planning to transit through Australia will have to arrive there by midday or else find a different route.

Roberts has a message for international visitors: "Get home as soon as you can. What you thought was possible yesterday may not be possible today, and if you don't have any way to get home use whatever support you have from a travel company that you've used to just try and assist you with your arrangements which will need to be put in place for an extended stay in New Zealand that you weren't expecting."

Air New Zealand confirmed it was discussing possible mercy flights with the government, but referred questions to the Ministry of Foreign Affairs and Trade.