Donetsk: Dozens of Australian Federal Police have arrived in Donetsk, the regional centre nearest to the MH17 crash site, amid questions about why is Canberra sending so many and about the legal standing of the deployment before a vote of approval by the Ukrainian parliament.

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. It was also reported that information from the aircraft’s black box is consistent with it being hit by a missile.

As a European analyst’s assessment that the Abbott plan for troops at the crash site was ''nuts'' went viral and questions were asked about the good sense of an Australian bid to secure 50 square kilometres with about 200 personnel, there was a subtle recasting of Canberra’s rhetoric on the profile of its deployment to a crash scene in the middle of a separatist war zone.

Last week Foreign Minister Julie Bishop told reporters in Kharkiv, the Ukrainian city from which the victim’s bodies were being airlifted to the Netherlands, that “of course we will ensure the [investigators’] are safe, that they will have protection".

On Sunday, Prime Minister Tony Abbott’s special envoy on the ground, former Air Chief Marshal Angus Houston, told reporters that Australian troops would not enter the crash site.

Explaining that Australia was days away from sending in a police-led, “non-threatening” force to recover bodies and assist with the investigation, he said: “One of the important things here is to posture a non-threatening force, [which] will go in with civilian specialists in white vehicles who will do the job on the crash site.

“One thing that we will be going in with is primarily police and civilians, not military personnel. Military personnel have been involved in some of the activity, but on this one it's a police-led mission and I think that's the right answer, and I think it's going to be very important to posture a non-aggressive, non-threatening force so that nobody will interfere with it.”

The hostilities between Ukrainian forces and rebels showed no sign of quieting. Government troops fought against rebels in Horlivka just 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 stop Perth couple Jerzy Dyczynski and Angela Rudhart-Dyczynski's from becoming the first family to visit the crash site on Saturday, after the loss of their 25-year-old daughter Fatima along with 287 other passengers 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 crash site than the 190 Australian Federal Police Mr Abbott plans to send.

Malaysia’s three-person team that visited the site 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 black box 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.''

Ms Bishop told Channel 10 that a number of those in the Australian operation to investigate the crash site would be armed to protect investigators, but did not say how many.

At about 11am, a six-vehicle convoy pulled into the Radisson Park Inn in Donetsk, disgorging 40 or more Dutch police and forensic experts who had driven from Kharkiv, a city a five-hour drive to the north of Donetsk which is in the control of the Kiev government.

They were ushered straight into what Fairfax Media was told was to be a joint briefing with the Australian contingent that arrived in Donetsk on Saturday evening, ahead of some or all of them making the 100km drive from Donetsk to the heart of the cash site.

By lunchtime none of the investigators or their OSCE had left their headquarters hotel in the city.

Wearing bright yellow vests emblazoned with the Australian flag, several of the Australian Federal Policemen conferred briefly with rebel fighters who ordinarily escort the foreign investigative teams to and from the site.

Hotel sources said that as many as 30 Australians had checked into the Radisson Park Inn in Donetsk on Saturday evening, but reports from Canberra cited a figure of 11 Australians being present in Donetsk