Justice Minister Amy Adams says she is seeking reassurances from her Australian counterparts that they are honouring their promise to help New Zealand detainees to return home as quickly and easily as possible.
Ms Adams said she planned to speak to Australian Immigration Minister Peter Dutton today.
"We ... want to talk him about making sure New Zealanders who want to come back to New Zealand from detention can do so easily and without barrier," she said.
She said Australian Prime Minister Malcolm Turnbull had given an assurance that New Zealand detainees could return home, that their applications would be handled "expeditiously", and that their return to New Zealand would not be detrimental to their appeals against deportation.
The minister now wanted Mr Dutton to update her on how he was advancing these assurances.
The Justice Minister met with Mr Dutton as recently as last week.
But she said the events on Christmas Island, where rioting broke out on Sunday, had created "increasing concerns" about whether New Zealanders were able to leave "easily and without prejudice".
New Zealand detainees at the offshore centre say frustration about delays in their processing were a factor in the riots, which were only just coming under control this morning.
Ms Adams said that regardless of the sentences which the New Zealand detainees had previously served, she expected basic standards to be upheld including access to consular services.
She also said some detainees at Christmas Island were considered high-risk, and it was important that New Zealanders were kept safe from these people.
They included people convicted of murder, rape, drug offences and child sex offences.
Prime Minister John Key called in foreign affairs officials last night to get a briefing on any barriers for New Zealand detainees who wanted to return home.
Mr Key said he had been told that detainees faced a wait of "weeks, not months" before they could return.
That was because some of them had been in prison for a long period and did not hold a passport. They might also be considered a security risk and could not travel commercially, or could have medical issues.
Australia was expected to arrange charter flights for some of the detainees. There was a possibility that some charter flights might take a single passenger.
Mr Key said Australia would pay for these flights because the deportations were a result of its policy change.
Up to 500 New Zealand ex-criminals are being considered for visa cancellation under a controversial Australian law change.
Around 40 of them were being held at the Christmas Island detention centre.