Tony Abbott has warned of evidence tampering on ''an industrial scale'' at the MH17 crash site, underscoring the massive challenge facing international investigators including Australians as they converge on Ukraine.
The bodies of the victims in the crash arrived at at the Ukrainian city of Kharkiv on Tuesday night Australian time, from where they will be flown with help from an Australian C-17 plane to the Netherlands.
And Moscow began laying the foundations of a counter-narrative for the crash by blaming the Ukrainian armed forces and dismissing suspicion of Russian involvement as ''a fabrication''.
Mr Abbott also called for an multinational security force of countries ''wronged'' in the crash - including Australia - to be deployed to guard the site, though his office later stressed there were no immediate plans to send defence or police personnel to the scene.
Crash investigators led by the Dutch and including two Australians were poised in Kiev for the all-clear to travel to the site and begin their work after the United Nations Security Council approved an Australian-sponsored call for the probe to begin free from harassment by local militias.
But Mr Abbott laid out the stark obstacles facing the investigation, bluntly calling the removal of evidence a cover-up, and warning there was a ''long, long way to go'' in the investigation.
''After the crime comes the cover-up. What we have seen is evidence tampering on an industrial scale and obviously that has to stop,'' he said.
Though he was more optimistic than he had been days ago, pointing to an apparent ceasefire between Russian-backed rebels and government forces, Mr Abbott did not rule out Australia sending in defence or federal police to the site.
The road ahead for the investigation appears to be bumpy, with the Russian government supporting the UN resolution for an open-minded investigation but then soon after issuing a statement effectively blaming the Ukrainian defence forces for shooting down the airliner.
The statement from Russia's Defence Ministry stated that a Ukrainian combat jet had been in the region at the time of the crash, which happened within range of Kiev's surface-to-air Buk missile systems. Video reported in international media of a Buk system being shifted from Ukraine to Russia after the crash was ''a fabrication''.
Mr Abbott and other world leaders have repeatedly blamed pro-Russian separatists for shooting down the plane, though he held back on such language on Tuesday, instead praising Russian President Vladimir Putin for being ''as good as his word'' in smoothing the way for the investigation and urging him to continue to do so.
But it remains unclear whether Mr Putin will use Moscow's influence over the separatist militia in the region to ensure they do not interfere further with the investigation.
Russia's ambassador to Australia, Vladimir Morozov, said Mr Putin had already vowed to ''do everything … to secure the work and secure the area where this tragedy happened''.
But he went on to deny that Moscow even had total influence over the separatists in the region, saying there had been occasions when Russia had not been able to influence the self-declared independent government. ''There is no direct link between what we ask and what they do,'' he said.
Mr Abbott also confirmed DNA samples were being taken from the families of victims to help identify remains.
The Australian C-17 military plane was sent to the Dutch city of Eindhoven from its base in the Middle East and will help a Dutch C-130 plane transport bodies back to the Netherlands.
Victims' remains retrieved from the crash site have been loaded onto refrigerated trains and are bound for the Ukrainian city of Kharkiv, from where they will be flown to the Netherlands.
International news reports have indicated that 282 bodies and 87 body parts have been loaded onto the trains. There were 298 victims of the crash.