Grabove, 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 Malaysia Airlines 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.
The train was headed to the city of Donetsk, Russian state news agency RIA Novosti reported Sunday evening.
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. Rebels are suspected of shooting down the plane with a Russian-made surface-to-air missile.
There were concerns the bodies had been picked over by thieves.
"The facts of looting, how the terrorists are dealing with the bodies, are beyond the moral boundaries," Ukrainian President Petro Poroshenko tweeted.
The local head of the rebels denied responsibility when asked about people reportedly using stolen bank-issued cards taken from the victims' bodies.
"It is possible that some local residents could have searched the bodies of victims, found their cards and tried to use them. Unfortunately, I can't exclude the possibility of this," Alexander Borodai said Saturday.
More order at crash site
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 hundreds of 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.
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.
Black boxes found?
Pro-Russia separatists may have recovered the plane's flight data recorders, Borodai said Sunday on the website of the self-declared Donetsk People's Republic. Borodai said if experts determine the devices found are the so-called black boxes, they would be turned over to international investigators.
"These are some technical objects. We cannot say for sure these are black boxes," he said, according to a CNN translation.
Borodai said the devices are under guard in the region. They will not be given to Ukrainian officials, he said.
The Reuters news agency distributed video on Sunday of what appeared to be an inflight recorder found by a worker in a field in eastern Ukraine. The agency labeled the video, shot Friday, as showing one of the two flight data recorders from MH17.
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