Prime Minister John Key has called on Russian President, Vladimir Putin to show leadership and tell Ukrainian rebels to back off and allow full access to the crash site of Malaysia Airlines flight MH17.
Mr Key made the statement at a news conference in Auckland on Sunday, confirming one New Zealander, and a New Zealand resident died in the crash.
He said the rebels must set up a corridor of access for crash investigators so all information on the crash can be gathered.
Mr Key said this was a time of enormous trauma and stress for the families involved and that was compounded by reports of passports and other information being removed from the crash site by the rebels.
He said the families deserved to see the recovery of the airline's flight recorder and for those responsible for the crash to be held to account. He said it was deeply concerning that a 24 hour ceasefire by the Ukrainian separatists was also failing.
Mr Key said he had been in telephone contact with the leaders of several countries about the lack of access to the crash site.
He said the leaders of many countries where victims of the crash came from, were standing united.
Mr Key has been in touch with the Prime Ministers of Australia, Malaysia and on Sunday night he will speak to the leader of the Netherlands about the situation.
Russian hold over rebels may be tenuous, says academic
Meanwhile, an Auckland academic says the disaster has thrown into doubt the influence Russia has over the separatist rebels being blamed for shooting the plane down.
Nicholas Ross-Smith, an Auckland University expert on the region, told TVNZ's Q + A programme it was obvious Russia was involved.
He said the rebels were using Russian hardware, and had the benefit technically and tactically of Moscow's support.
But Mr Ross-Smith told the programme Russian control of the rebels may now be tenuous, with a picture emerging of forces which were undisciplined, and something of a rabble.
He said Vladimir Putin would probably want to appease the West over its calls for full access to the site, but he was under pressure, after using anti-Western rhetoric in Russia to build support for his leadership.
Australia's Foreign Minister to campaign for investigation
Australia's Foreign Minister, Julie Bishop, is heading to the United States to campaign for an international investigation into the crash of the Malaysia Airlines plane in eastern Ukraine.
Twenty-eight Australian citizens and eight permanent residents were among the nearly 300 people on board when flight MH17 was apparently shot down this week.
The ABC reports that Ms Bishop will launch a lobbying offensive at the United Nations in New York, and call for Security Council members to back a binding resolution on the investigation.
Australian Prime Minister Tony Abbott said he feared the chaos at the site would continue, despite Russia's agreeing to co-operate with an inquiry.