More human remains have been found and wreckage uncovered during a visit of three Australian officials to the MH17 site in eastern Ukraine.
Prime Minister Tony Abbott on Friday inspected the Australian Federal Police operations room in Canberra where Operation Bring Them Home is being co-ordinated.
"Previously undiscovered wreckage has been found and I regret to say more human remains have been found and we expect that further remains will be found in the days ahead," Mr Abbott said.
He said this made it more important than ever to properly secure the site.
Currently 90 AFP officers have been pre-deployed to Europe under a Dutch-led investigation.
Australia is close to finalising an agreement with the Ukraine for the deployment of Australian police, some of whom will be armed, to the investigation.
A further 100 AFP officers are to be sent on Friday.
Mr Abbott said some Australian Defence Force personnel would accompany the police, but this did not make it a military operation.
"This is a police-led mission," Mr Abbott said.
"It would be an international police-led mission and it's a humanitarian mission to ensure that we bring (the crash victims' bodies) back."
He said problems within the Ukrainian government, including the resignation of the prime minister, would not impact on negotiations on the security agreement.
"We are very close to finalising a memorandum of understanding with Ukraine with the president of the Ukraine - that is what is required under Ukrainian law."
There are now more than 200 Australian personnel abroad as well as hundreds in Canberra working on the operation.
Mr Abbott said Australia was working with the many nations that lost citizens.
"This is a humanitarian mission, with a clear and simple objective," he said.
"I expect the operation on the ground in Ukraine, should the deployment go ahead, to last no longer than a few weeks."
AFP Commissioner Tony Negus said this would be one of the largest delegations of AFP officers since the Bali bombing.
He said over the next 24 hours another 100 AFP officers were getting ready for deployment for any international mission should it go ahead to secure the site.
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