The suspension will take effect from midnight on Thursday (NZST) and be "constantly reviewed" according to COVID-19 Minister Chris Hipkins.

"We do need more information I think at this point," Mr Hipkins said.

"We've weighed this up very carefully, it's a finely balanced decision, because we do acknowledge that this has the potential to disrupt people's travel."

The pause is the second hit to the trans-Tasman bubble since coming into effect last month.

Last week, travel from Western Australia was paused after a quarantine worker and his housemates tested positive to COVID-19.

In this case, a Sydney husband and wife have tested positive to the deadly virus, with health authorities yet to identify a "missing link" between them and hotel quarantine.

New Zealand's restrictions - which apply to the whole of NSW - are tighter than other Australian states.

Western Australia, Queensland, Victoria and Tasmania have only slapped bans on movement of people from exposure sites visited by the new Sydney cases.

""Our health teams do compare notes on all of those things ... we're erring on the side of caution," Mr Hipkins said.

The travel pause does not apply to travellers from New Zealand to NSW.

However, travel to Sydney looks set to be hit, with airlines likely to change flight schedules as a result.

"If people are going to New South Wales, those are calls for them to make ... should they go ahead and travel to Australia they should follow the public health advice of Australian officials," Mr Hipkins said.

He said he was confident the pause would only last until midnight on Saturday, with more information about the "missing link" likely to be identifed.

"I've got a lot of confidence in the New South Wales contact tracing system," he said.

"If we don't know more (in the next two days) that in itself may be a message but we've just got to let them do their job."

Around 6000 people have travelled to New Zealand from Sydney since the emergence of the case.

"Unless they've been in a location of interest, the risk is very low," Mr Hipkins said.

Australian Associated Press