The Australian state of Victoria has recorded four new cases of COVID-19.
Victorian Chief Health Officer Brett Sutton confirmed the new cases to ABC Melbourne on Tuesday evening.
All of the new cases are household contacts of the fifth case which was reported on Tuesday morning.
Sutton told ABC Melbourne it's too early to tell whether there will be more cases.
"We've got a number of primary close contacts that we are following up with now, so we have to be alive to the possibility that more of those will be confirmed positive."
He said all the primary close contacts are in quarantine and the outbreak isn't out of control.
This comes after COVID-19 Response Minister Chris Hipkins confirmed the quarantine-free travel bubble between Victoria and New Zealand would be paused from 7:59pm NZT on Tuesday for 72 hours.
He said it would be paused while the source of infection of the five cases continues to be investigated.
The Director-General of Health Dr Ashley Bloomfield told Newshub they had seen Victorian authorities bringing in more restrictions for residents as they believed the virus may be more prevalent in the community, which had helped the New Zealand Government decide to pause the bubble.
"I think our advice on balance is right here. It's proportionate and it's in line with what the Victorian authorities are doing in Melbourne."
He confirmed there are "no plans" currently to pause travel with other Australian states.
Dr Bloomfield said he imagined many people would be affected by the bubble pause, but said it's ultimately important to keep the virus out of New Zealand.
"I imagine there are three or four flights, if not more each day, which go from Melbourne to different parts of New Zealand so there will be Kiwis affected who were planning to travel back, but also Australians who were planning to visit New Zealand."
When asked if the pause of 72 hours is enough, Dr Bloomfield said he believes it is for now and authorities will consider making it longer if the situation changes.
"Seventy-two hours is our initial advice but we will keep an eye on it on a daily basis. If we think there is an indication to extend it, we wouldn't hesitate to update our advice."