Pro-Russian militiamen in Ukraine have loaded almost 200 bodies from the downed Malaysian jet into trains and say they’ve recovered objects from the crash site believed to be the plane’s black boxes.

Grieving families were clamouring to have their loved ones brought home, as concerns mounted that the rebels were still limiting access to the bodies and hiding key evidence from Thursday’s disaster.

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European leaders again warned Russia to ensure rescuers and investigators have full and unfettered access to the crash site in rebel-held eastern Ukraine or face further EU sanctions.

Malaysia Airlines flight MH17 was blown out of the sky by what is believed to be a surface-to-air missile, killing all 298 passengers and crew and dramatically raising the stakes in Ukraine’s bloody three-month conflict.

“Jet parts resembling the black boxes were discovered at the crash site,” said Alexander Borodai, prime minister of the self-proclaimed Donetsk People’s Republic, adding that they would be handed over to “international experts if they arrive”.

Organization for Security and Co-operation in Europe (OSCE) monitors escorted by armed rebels appeared on Sunday to be granted greater freedom to examine the site in Grabove.

Borodai said the fighters had moved scores of bodies “out of respect for the families” and loaded them on to trains where they would be kept in refrigerated carriages until “the experts arrive”.

“We couldn’t wait any longer because of the heat and also because there are many dogs and wild animals in the zone.”

The OSCE observers said they found the corpses packed into refrigerated wagons at a station in the town of Torez, some 15km from the crash site.

Spokesman Michael Bociurkiw described the stench at the station, where armed separatists were guarding the grisly cargo, as “almost unbearable”.

The bodies, some dismembered and charred, had been left rotting in cornfields amid the blackened piles of mangled wreckage of the plane, with debris spread out for kilometres.

At the railway station the team observed three refrigerated rail cars holding bodies, Mr Bociurkiw told reporters in a conference call on Sunday.

“We were told there were 169 bodies there although we have no way of independently verifying that,” the OSCE spokesman said.

Almost 300 people perished when the plane was downed on Thursday.

Mr Bociurkiw said if the bodies at Torez were indeed MH17 victims it was a positive development because there were all being kept in one location.

He suggested they were moved on Saturday night or very early on Sunday morning.

“We were further told that the plan now is to keep those railway cars there and allow in international experts and then at that time a decision will be made where to take them,” the mission spokesman said.

“They were wondering when experts will be arriving to start processing the bodies.

“The thinking is the cars should be taken to Ukrainian-controlled territory, such as Kharkiv, and they can be processed there.”

Mr Bociurkiw said there appeared to be a preparedness to listen to international experts – from the Netherlands, Malaysia and other countries – and follow their guidance.

The railway cars were from Soviet times but there was no doubt they were refrigerated with power coming from the locomotive, he said.

The body bags the team saw were tagged with numbers.

But Mr Bociurkiw stressed it was not possible to enter the cars without professional protective equipment.

“The issue is what kind of security will be provided to the experts to actually get to this region where we are now.”

The spokesman said the monitoring mission could try and facilitate that movement because it had “fairly good relationships with the people in charge”.

The team on Sunday was escorted to the railway station by armed guards from the Donetsk People’s Republic.

Back at the crash site Mr Bociurkiw said the body bags that had been previously on the ground had been removed.

He added that some bodies appeared to have been “vaporised”.

“Not only bodies, but also parts, the heat must have been so intense.”

He added that at the site there was now plastic tape around some areas that wasn’t there on Saturday which was a “huge development”.

Russian news agencies, however, report the bodies are heading to the rebel stronghold of Donetsk.

– AAP