HRABOVE, Ukraine (AP) -- Dutch experts called Monday for a full forensic sweep of the site where Malaysia Airlines Flight 17 went down and told armed separatists guarding rail cars full of victims' bodies the train must be allowed to leave as soon as possible.
Four days after the Boeing 777 was shot out of the sky, international investigators still had only limited access to the crash site, hindered by the pro-Russia fighters who control the verdant territory. Pressure was growing on Russian President Vladimir Putin -- who the U.S., Ukraine and others say has armed the Russian-speaking rebels -- to rein in the insurgents and allow a full-scale investigation into the downing of the plane.
Russia has denied backing the separatists.
In Washington, President Barack Obama demanded that international investigators get full access to the crash site and accused the separatists of removing evidence.
"What exactly are they trying to hide?" he asked, a day after the U.S. presented what it called "powerful" evidence that the rebels shot down the plane with a Russian surface-to-air Buk missile.
In farm fields near the eastern village of Hrabove, Peter Van Vilet, leader of the Dutch National Forensic Investigations Team visiting Ukraine, said seeing the crash site was an emotional experience that gave him goose bumps despite the heat.
The team -- which specializes in victim recovery and identification -- observed some victims' remains that had not yet been removed from the crash site and pressed the rebels to seal the refrigerated train cars parked in the rebel-held town of Torez, 15 kilometers (9 miles) away.
The Dutch team also inspected the plane luggage gathered at the crash site and suggested it be put in a container and shipped out.
At the U.N. in New York, the Security Council will vote later Monday on an Australia-proposed resolution demanding international access to the crash site and a cease-fire around the area. Australian Prime Minister Tony Abbott said his country would view a Russian veto of the resolution "very badly," adding that "no reasonable person" could object to its wording.
At the Torez train station, the Dutch investigators stood for a moment with their heads bowed and their hands clasped before climbing aboard to inspect the train cars, surrounded by armed rebels.
There is great concern in the Netherlands about the bodies, since 192 of the plane's 298 victims were Dutch and another was Dutch-American. Dutch Prime Minister Mark Rutte said Monday that repatriating the bodies was his "No. 1 priority."
AP journalists said the smell of decay was overwhelming at the Torez train station and many with the inspectors wore masks or pressed cloths to their faces on the sunny, 84 degree Fahrenheit (29 degrees Celsius) day. A Ukrainian train engineer told The Associated Press that a power outage had hit the rail cars' refrigeration system for several hours overnight but the power was back up Monday.
"I think the storage of the bodies is of good quality," Van Vilet said. "We got the promise the train is going."
It was not clear where the train would go. The Ukrainian government is hoping it will go to the government-controlled eastern city of Kharkiv, where it has set up a crash crisis center, but the rebels have not confirmed any movement yet.
In Kharkiv, another team of international experts arrived, including 23 Dutch, three Australians, two Germans, two Americans, and one person from the U.K.
At the charred crash site itself, emergency workers retrieved 21 more bodies Monday, bringing the total to 272 bodies, Ukrainian Prime Minister Arseniy Yatsenyuk said.
But fighting flared again between the separatists and government troops in the eastern rebel-held city of Donetsk, just 50 kilometers (30 miles) to the west of the crash site. City authorities said battles were taking place Monday near the town's airport. An AP reporter heard several explosions and saw smoke rising from that direction.
Fighting began in mid-April between the government and the Russian-speaking separatists in eastern Ukraine after Russia annexed Ukraine's Crimean Peninsula a month earlier.
The U.S. evidence that the rebels were involved in downing the plan included video of a rocket launcher, one surface-to-air missile missing, leaving the likely launch site; imagery showing the firing; phone calls claiming credit for the missile strike and phone recordings said to reveal a cover-up at the crash site.
"A buildup of extraordinary circumstantial evidence ... it's powerful here," said U.S. Secretary of State John Kerry. "Russia is supporting these separatists. Russia is arming these separatists. Russia is training these separatists."
Putin lashed out against the criticism Monday, accusing others of exploiting the downing of the plane for "mercenary objectives."
Putin said Russia was doing everything possible to allow a team of experts from the International Civil Aviation Organization, a U.N. agency, to investigate the scene. He again criticized Ukrainian government authorities in Kiev for reigniting the fighting with the rebels.
"If fighting in eastern Ukraine had not been renewed on June 28, this tragedy would not have happened," Putin said. "Nobody should or does have a right to use this tragedy for such mercenary objectives."
The head of counterintelligence for Ukraine's SBU security service, Vitaliy Najda, said the Buk missile launchers came from Russia and called on Russia to supply the names of the service personnel "who brought about the launch of the missile" so they could be questioned. He said the rebels could not have operated the sophisticated weapon without Russian help but did not provide specific evidence for his claim.
In Moscow, Russian officials offered evidence Monday to counter U.S. claims that the rebels were responsible for shooting down the jet. The Defense Ministry showed photos they said proved that Ukrainian surface-to-air systems were operating in the area before the crash -- nine times alone on Thursday, the day the plane was brought down.
Russian officials also said they had evidence that a Ukrainian Sukhoi Su-25 fighter jet had flown "between 3 to 5 kilometers (2 to 3 miles)" from the Malaysia Airlines jet.
"(The plane) is armed with air-to-air R-60 rockets, which can hit a target from a distance of up to 12 kilometers (7 miles) and guaranteed within 5 kilometers (3 miles)," said the chief of Russia's General staff, Andrei Kartopolov.
The defense ministry officials also insisted that Russia had not given the rebels any surface-to-air missiles and added they have no evidence that any missiles were launched at all. They asked the U.S. to share any satellite images of the launch.
In the Netherlands, victims' families were being consoled by the Dutch royals on Monday.
McHugh contributed from Kiev. AP staff writers Laura Mills and Nataliya Vasilyeva reported from Moscow and Mike Corder contributed from The Hague, Netherlands.