A former top cop has called on authorities to re-interview the two women who tested positive for Covid-19 after leaving quarantine, saying their story leaves more questions than answers.

The new Covid-19 cases are two women who flew in from the UK and travelled to Wellington to grieve the sudden passing of their parent, director-general of health Ashley Bloomfield said.

They were allowed to leave their managed isolation at the Novotel Ellerslie in Auckland without being tested on the condition that they were tested in Wellington, which returned positive results.

One of the women had mild symptoms before being tested, but it was put down to a pre-existing condition.

But with questions surrounding the women's account, Lance Burdett, an ex-police negotiator, has called on authorities to look at video evidence to make sure they're telling the truth.

He told the Herald he would be hesitant to say the pair didn't stop anywhere and authorities need to determine whether they are trustworthy.

"It would be a long shot anyway but you'd have to know the route they'd taken.

"In the first instance what I'd do is re-interview the pair, but doing an interview that is called an investigative interview. You outline the information you want and in this case the gravity of the situation. But you do it in a conversational format."

Lance Burdett, a former police negotiator, says the two women who were allowed to travel despite having Covid-19 need to be reinterviewed to make sure their story checks out. Photo / Supplied

• National MP: Covid women's story about road trip 'not accurate'

Burdett says while the pair have done nothing wrong, their story contains a number of holes that need to be checked out and video evidence would be able to help identify if the truth is being told.

"From what it looks to me is the pair have done nothing wrong, except they might have lied. I would doubt you could drive from Auckland to Wellington and not stop off to stretch your legs.

"You can have food and liquid in your car, but you're looking at an 8.5 to 10-hour drive without going to the toilet. You must have stopped off to go toilet. Where did you stop off?

"Did you stop off on the side of the road? Okay, that's fine. If it was a public toilet, which toilet? Did you get food from anywhere? I would be questioning them on that. That would give you the idea of whether the person in front of me telling the truth. What's the likelihood of someone doing that?

"I'd be hesitant on saying they didn't stop off anywhere. Our first reaction is to go into defence mode. That could bring out some untruths. We won't know until you interview them.

"You can get from Auckland to Wellington on one tank of gas. Where's the most likely place they'd have stopped? Start looking at the service stations that are on the main highway. I would doubt they're going to go to a cafe given they need to get somewhere.

"You said you didn't stop. Are you sticking to your story?

"If they stick to their story, and there's no reason to discount them, but that's a long haul without stopping."

Burdett believes authorities could easily sift through surveillance footage because they have a time stamp on the pair's movements.

"Starting from the point of origin you could check the hotel footage. You'd know what time they left and what car.

"From Auckland to Hamilton the main road is two hours. You can check the service stations around the time they were due to pass, and then onto Taupō after four hours and so on. That would give you a time stamp.

"No offence has been committed but there is an element of doubt over the detail of their story."

On Tuesday, it was revealed the women were not tested before they left on the condition they were tested in Wellington, which returned positive results.

The border blunder has caused widespread outrage.

Prime Minister Jacinda Ardern said in a Facebook Live post on that standards had not been met, but stressed the women did nothing wrong.

"This case is clear - our expectations ... have not been met in this instance," she said.

The women said they did not stop for fuel or supplies on their road trip. They apparently took a toilet stop on the side of the road.

Ardern acknowledged the two women should not have been granted compassionate leave.

"That is something that we have taken incredibly seriously."

On Wednesday, Dr Bloomfield revealed there have been 320 close contacts identified with the two new Covid-19 cases.

Most of their contacts will be contacted by the end of the day and will be encouraged to be tested.

Bloomfield said he took responsibility for the failures that led to the two new cases.

"As director general of health, I have overall system responsibility for the health operations of our self-isolation facilities and exemptions.

"In this instance, these individuals should have been tested prior to leaving the managed isolation facility.

"I am taking responsibility for ensuring this does not happen again."