A vaccinated Masterton health worker who tested weak positive for Covid-19 has returned a negative second test, the Health Ministry says.

Covid-19 Response Minister Chris Hipkins said at today's media briefing that the case was under investigation. There were no community Covid cases in NZ today.

Earlier, Masterton Mayor Lyn Patterson said she understood from the 1.30pm briefing the local health worker was an unlikely case, but it may make some people in the area feel a little anxious.

Patterson said generally people had become a bit more relaxed around scanning QR codes.

"This is a timely reminder that we can't afford to be complacent," she said. "Hopefully those with Bluetooth capabilities have that switched on.

"We think we will remember where we have been, but it might be popping into the dairy to pick up a litre of milk – in and out. You may forget to scan. We can't afford to do that now."

"It's [Covid-19] going to be with us for a long time. We have to keep ourselves, our families and our communities safe."

Level 2 extended in Wellington

Alert level 2 rules will be extended for 48 hours in Wellington, Hipkins said at today's 1pm update, adding that NZ wasn't out of the woods yet.

Hipkins said it's possible that the alert level will go down at midnight on Tuesday based on the test results so far.

Wellington was moved to alert level 2 on Wednesday at 6pm. That level was originally hoped to be lifted at midnight tonight.

The vast majority of the more than 2000 contacts of the Sydney traveller who tested positive for Covid-19 have returned negative tests, Hipkins said.

Testing turnout in Wellington has been low, and Hipkins encouraged more people to be tested in the capital. New locations of interest have been announced.

Mask use is encouraged where social distancing is not possible.

NSW authorities confirmed the partner of the Covid-positive man who travelled to Wellington has now tested positive.

Aussie travel ban

Hipkins foreshadowed pre-departure testing was likely to be introduced once the transtasman bubble was reopened. The Government would consider whether the testing rule would be implemented across Australia.

"Hold tight and follow public health advice," Hipkins said to Kiwis stranded in Australia.

People who have returned from Sydney are asked to keep to Sydney restriction rules.

Yesterday, Hipkins announced the transtasman quarantine-free travel bubble would be halted for three days starting at 10.30 last night.

The standstill marks the first time the bubble to all Australian states has been paused.

The ban on quarantine-free travel from all Australian states and territories is currently set to lift at 11.59pm (NZT) on Tuesday, June 29.

An exposure event at a Northern Territory gold mine was the tipping point for the transtasman bubble to close, Bloomfield said.

A worker at the mine yesterday tested positive for Covid, sparking concern for over 900 workers who have already left the site.

Hipkins said there was potential for the virus to have spread across Australia from this event and potentially into New Zealand.

The Northern Territory this afternoon announced a 48-hour lockdown for Darwin and Palmerston after four new locally acquired Covid cases were detected.

Greater Sydney and other parts of NSW went into a two-week lockdown at 6pm last night. The state recorded 30 new community Covid cases today.