National leader Bill English said the risk of re-offending was why National moved to put a supervisory regime over the most serious of those criminals.
"You can see why Australia wants some of these people out of their country and it's unfortunate that we're the country they're being sent to.
"In my view, the re-offending rate could have been higher. But it does show some of them are a real challenge and I'd hope the new Government continue with the same level of supervision and hopefully improve it."
Australia's policy changed in 2015 so that anyone not an Australian citizen and who had served more than a year in prison would be deported. Others were being deported on character grounds.
About 175 New Zealand citizens are in detention centres such as Christmas Island awaiting the outcomes of appeals or deportation.
At the start of the new policy Australia had taken a hard line stance but Ardern said that had eased after Australia Prime Minister Malcolm Turnbull agreed to look at the appeal system, including the length of time someone had spent in New Zealand.
Ardern said the rate for deportee reoffending was in line with overall offending rates.
Labour was highly critical of the Australian policy when in Opposition, including the time New Zealanders spent in detention centres while awaiting their appeals. Corrections Minister Kelvin Davis had visited Christmas Island to meet them.
The previous National Government had to rush to introduce new supervisory powers in 2015 to allow Police to keep an eye on the most serious of those criminals returning.