HRABOVE, Ukraine (CNN) -- Twenty-seven more bodies have been found at the MH17 crash site in the Donetsk region of Ukraine, Vice Prime Minister Volodymyr Groysman said Sunday. That brings to 233 the total number of bodies recovered from the passenger jet, which was shot down on Thursday.
Pro-Russia separatists are keeping the remains of 192 of those MH17 victims in refrigerated cars on a train, Groysman said, adding that talks are ongoing for their release.
Meanwhile confusion is still rife over the state of the investigation into the crash of the downed plane, which killed all 298 people on board.
The State Emergency Service said the search in the remote area of eastern Ukraine, roughly 40 kilometers (25 miles) from the Russian border, was being "complicated by armed separatists at the site who hinder the work of SES units."
It said that 380 official staff members are taking part in the search for the remains of the MH17 victims, covering an area stretching across 34 square kilometers (13 square miles).
They were being helped by busloads of volunteers from local coal mines who fanned out across the wheat fields where the bodies and debris from the plane fell to earth Thursday.
The situation at the crash site showed some small signs of improvement, with more control and more activity. But it was still far from a well-organized investigation scene, and the area was still under the control of pro-Russia rebels.
Many of the bodies that had littered the fields previously were gone by late morning Sunday as CNN teams observed the crash site, but it was not immediately clear where they had been taken.
Government emergency workers prevented vehicles from driving up the road to the main crash site, but people could still roam around the fields on foot.
U.S. Secretary of State John Kerry told CNN's "State of the Union with Candy Crowley" that there were reports Sunday of "drunken separatists piling the remains of people into trucks in an unceremonious fashion."
He said he spoke Saturday with Russian Foreign Minister Sergey Lavrov in what he called a "direct and tough conversation."
Russia needs to help ensure that investigators can conduct a thorough investigation, he said.
Bodies on train cars
Large numbers of bodies have been collected on refrigerated train cars at a station near the crash site, international observers told CNN.
The observers, from the Organization for Security and Co-operation in Europe, said they have been told the bodies are from the crashed plane but they can't independently confirm that.
The 14-member OSCE team said the train will remain in place until international specialists arrive. It was not clear when that would be or where the train might take the bodies.
It's hard to get reliable information at the scene because several groups of pro-Russian rebels, some of them masked, control the checkpoints leading to the crash site.
"There doesn't seem to be one commander in charge," Michael Bociurkiw, a spokesman for the OSCE observers, told CNN on Saturday.
Rebels are suspected of shooting down the plane with a Russian-made surface-to-air missile.
Three air crash investigators from Ukraine accompanied the OSCE observers on Saturday but didn't have much time to do their work, Bociurkiw said. "They need a lot more time and a lot more freedom of access," he said.
Where are the 'black boxes'?
The Reuters news agency distributed video on Sunday of what appeared to be an inflight recorder found by rescue workers in a field in eastern Ukraine. The agency labeled the video as being of one of the two flight data recorders from MH17.
The Ukrainian government said Friday -- the same day the Reuters video was shot -- that the so-called black boxes are still in Ukrainian territory but didn't clarify whether they were in Ukraine's possession.
Bociurkiw said then that no one at the crash site was able to tell his people where the recorders might be.
Malaysian investigators flew to Kiev, the Ukrainian capital, on Saturday. But Malaysia's official news agency Bernama said they were still negotiating with pro-Russian rebels over access for their 131-member team.
Malaysian Transport Minister Liow Tiong Lai said Saturday in Kuala Lumpur that Malaysia was "deeply concerned that the crash site has not yet been properly secured."
"There are indications that vital evidence has not been preserved in place," he said.
Law enforcement officials from the Netherlands, the United States and Australia have arrived or are being sent to Ukraine to work with the investigation, which is being led by the Ukrainian government in Kiev.
Malaysia Airlines said Sunday that it will retire the flight number MH17 for the route from Amsterdam to Kuala Lumpur, replacing it with the code MH19.
Families' agonizing wait
For the families of the victims, the confusion at the scene of the crash deepens the suffering.
Silene Fredriks said her son and his girlfriend had taken Flight MH17 for a planned vacation in Bali. At Amsterdam's Schiphol Airport on Sunday, she laid flowers and
signed the condolence book.
She says she wants Russian President Vladimir Putin to ensure that the two young people's remains make it back to the Netherlands.
"Mr. Putin must take care of my son and my daughter to bring them home," she said. "I can do nothing but wait for their bodies."
The lack of clear information about what's happened to the victims is "horrible," she said: "It's one bad movie."
Pressure on Putin
Governments from around the world have expressed outrage at the disorderly situation at the crash site and called on Putin to use his influence on the pro-Russian rebels.
"There are multiple reports of bodies being removed, parts of the plane and other debris being hauled away, and potential evidence tampered with," the U.S. State Department said in a statement. "This is unacceptable and an affront to all those who lost loved ones and to the dignity the victims deserve."
British Prime Minister David Cameron wrote a Sunday Times opinion article urging Putin to find a way to make the crash site more accessible and calm the strife between Ukraine and the rebels.
"If President Putin does not change his approach to Ukraine, then Europe and the West must fundamentally change our approach to Russia," Cameron wrote. Ten of the passengers on MH17, which was en route from Amsterdam to Kuala Lumpur, were British.
Australian Prime Minister Tony Abbott, whose country had 27 citizens on the plane, added to the pressure on Putin.
Describing the downing of the passenger jet as "a horrific crime," Abbott said he had summoned Russian Trade Minister Denis Manturov, who is visiting Australia, and "made crystal clear my concerns and dissatisfaction with the way this has been handled."
"Russian-controlled territory, Russian-backed rebels, quite likely a Russian-supplied weapon," Abbott said in a television interview Sunday. "Russia can't wash its hands of this."
German Chancellor Angela Merkel and Dutch Prime Minister Mark Rutte have spoken out, as well.
"I want to see results in the form of unhindered access and a speedy recovery of the victims' remains," Rutte said Saturday. Nearly two-thirds of the people on the jetliner were Dutch.
Rutte told reporters he had "an extremely intensive telephone conversation" with Putin on Saturday in which he told the Russian leader that "the window of opportunity to show the world that he intends to help is closing rapidly."
The United States has said evidence suggests a Russian-made surface-to-air missile fired from the rebel territory took down the Malaysia Airlines Boeing 777 with citizens from more than 10 nations aboard.
"It's pretty clear that this is a system that was transferred from Russia in the hands of separatists," Kerry told CNN on Sunday.
U.S. officials believe the missile systems may have been moved back across the border into Russia, CNN foreign affairs reporter Elise Labott said Saturday.
Russia has denied any involvement, and Putin said Ukraine's military campaign against the rebels was to blame. He also has called for a "thorough and objective investigation" of the crash.
Since the crash, the Ukrainian government and pro-Russian rebels have traded bitter accusations over who was responsible and what has been done since.
Ukrainian officials have said that a Russian-made Buk M1 missile system, brought into eastern Ukraine from Russia, had shot down the Malaysian airliner.
The Ukrainian government has accused the rebels of removing debris and 38 bodies from the scene as part of an attempt to cover up what happened.
The local head of the rebels, Alexander Borodai, has rejected accusations that his forces shot down the plane, telling reporters that the rebels lacked the firepower to hit an aircraft that high.
Borodai, who calls himself the prime minister of the self-styled Donetsk People's Republic, also denied that his forces removed any bodies.
CNN's Phil Black reported from Hrabove, Steve Almasy and Ralph Ellis reported and wrote from Atlanta, and Jethro Mullen reported and wrote from Hong Kong. CNN's Aliza Kassim, Richard Greene, Kellie Morgan, Victoria Eastwood, Erin McLaughlin, Antonia Mortensen, Laura Smith-Spark, Tom Cohen and John Raedler contributed to this report, as did journalists Victoria Butenko and Azad Safarov.
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