Up to 170 Australian Federal Police officers will deploy as part of a Dutch-led operation after Russian-backed separatists agreed to allow the so-called coalition of the grieving into the war zone to collect their dead and investigate the wreckage of the downed aircraft.

“Our objective is to get in, get cracking and get out,” said Mr Abbott.

“This is a risky mission, no doubt about that, but all the professional advice I have is that the safest way to conduct it is unarmed, as part of a police-led humanitarian mission.”

Eleven Australians in a 49-strong assessment team were due to be on the ground late Sunday, Australian time.

Dozens of AFP officers have arrived in Donetsk, the regional centre nearest to the MH17 crash site, from where they are expected to deploy after the assessment team inspects five wreckage sites in a 35-square-kilometre area where nearly 300 passengers died.

The AFP team was milling in the lobby of the Radisson Park Inn late on Saturday, on a day that saw only a few kilometres down the road the Ukrainian military fighting to retake a nearby city from Russia-aligned separatists.

Mr Abbott said that advice from his special envoy on the ground in the Ukraine, Air Chief Marshal Angus Houston, was that going into the war-torn area outside Donetsk was “eminently doable”.

“I've had advice from the Office of National Assessments that while there are risks, they can be mitigated and managed,” he said.AFP Commissioner Tony Negus agreed that the safest way to recover bodies and conduct an air crash investigation in what is expected to be a two to three-week window is unarmed and without military personnel on site.

The weekend negotiations were conducted on Australia’s behalf by the Organisation for Security Cooperation in Europe (OSCE) in the Ukrainian city of Donetsk.

Mr Abbott said on Sunday he had been in contact over the past 24 hours with Russian President Vladimir Putin and President Petro Poroshenko of Ukraine.

He had also had further communications with Prime Minister Mark Rutte of the Netherlands and Prime Minister Najib Razak of Malaysia.

Mr Abbott was at pains to stress that the police-led mission has “nothing to do with the politics of Eastern Europe”. ''We will stay as long as we can to do a professional job, but we won't stay a moment longer than we need to. We won't stay a moment longer than we absolutely need to,” he said.

Air Chief Marshal Houston said AFP officers would enter the border territory of the crash site to underline the “non-threatening” nature of the operation.

The hostilities between Ukrainian forces and rebels showed no sign of quieting. Government troops fought against rebels in Horlivka just kilometres outside of Donetsk, home to the separatist-dubbed "Donetsk People's Republic."

The push by the Ukrainian armed forces follows what Colonel Andriy Lysenko, Speaker for the Ukrainian Security, claimed were successful operations in 10 other localities.

“We will not bombard Donetsk. We will use only ground forces there, which will, street after street, quarter after quarter, free the city,” he said on Saturday.

The danger on the ground didn't keep Perth couple Jerzy Dyczynski and Angela Rudhart-Dyczynski from becoming the first family or friends to visit the crash site on Saturday, after the loss of their 25-year-old daughter Fatima along with 287 other passenger and crew.

But the prospect of urban warfare underscores the volatility of eastern Ukraine, a place where Malaysia believes far fewer investigators need to be deployed to the MH17 crash site than the 190 Australian Federal Police Mr Abbott plans to send.

Malaysia’s three-person team that visited the site on three days last week reported on the need for a significantly smaller investigative effort - at least 30 additional investigators need to be deployed in addition to themselves, three Dutch investigators and one official of the Organisation for Security and Co-operation in Europe.

Unreleased data from a flight data recorder retrieved from the MH17 wreckage show findings consistent with the plane's fuselage being hit multiple times by shrapnel from a missile explosion.

"It did what it was designed to do," a European air safety official said of the missile, "bring down airplanes."

The official described the finding as "massive explosive decompression."

That conclusion was consistent with more evidence from the crash site, of the blast holes through the body of the aircraft of the kind that would be inflicted by an exploding missile.

Joerg Forbrig, a defence analyst at Berlin’s German Marshall Fund of the US, said it would be “nuts” to send in armed troops and a senior Australian defence figure also warned against any expectation that Australians could secure the site.

''It's kilometres long and wide. They could escort Australian officials and provide close protection, but this is a civil task rather than a military task and it's a terribly volatile area.''