HRABOVE, Ukraine -- International monitors who have finally gained full access to the Malaysia Airlines crash site in eastern Ukraine said Tuesday the Boeing 777's cockpit inexplicably had been sawed in half while under the control of Russian-backed separates.
The monitors said they are not sure why the major piece of evidence from the downed plane was tampered with.
Flight 17, carrying 283 passengers and 15 crew members, crashed Thursday after being hit by what U.S. officials suspect was a surface-to-air missile launched from an area controlled by Russian-backed separatists.
The separatists and Russia have denied shooting down the plane, which was flying from Amsterdam to Kuala Lumpur.
The cockpit was found in a section of the crash site that had been immediately cordoned off during the first two days after the plane went down. Witnesses tell USA TODAY that this was also the area where the first bodies were removed.
The cockpit apparently was cut in half with diesel-powered saws.
"The rear part of the aircraft, one of the biggest intact pieces, has definitely been hacked into," said Michael Bociurkiw, spokesman for the group of international monitors from the Organize for Security and Cooperation in Europe (OSCE).
On Monday, President Obama had called on Russia on Monday to get separatists to stop hampering the crash investigation and allow international experts free access to the crash site.
"The separatists are removing evidence from the crash site," he said. "All of which begs the question: What are they trying to hide?"
In a related development, Dutch Foreign Minister Frans Timmermans said Tuesday in Brussels that the European Union is imposing new sanctions against officials deemed responsible for Russia's actions in Ukraine.
Timmermans said the EU's "forceful decision" imposes visa bans and asset freezes on more officials.
He says the ministers also asked the 28-nation bloc's executive arm to prepare for more forceful economic sanctions — including targeting the arms, energy and financial sectors — if Russia fails to back down from destabilizing Ukraine.
Timmerman did not specify how many officials were targeted under the latest sanctions, nor did he reveal their names.
After a four-day standoff, international teams were allowed into the crash site to look for more bodies and to gather evidence, but are cognizant of the political upheaval in the area, which Russia-back rebels have claimed as independent of Ukraine.
"It has been a different group of separatists every day, it is very difficult to actually get any insight as to which battalion or which group they belong to," Bociurkiw said.
More than 200 bodies of victims have been taken from the site and sent by refrigerated rail cars to the Ukrainian city of Kharkiv, where they are expected to be transported by a cargo plane on Wednesday to The Netherlands. Nearly two-thirds of the victims were Dutch citizens.
Small teams continue to search for more bodies from among the 298 victims, but monitors suggested that it could take months to scour the crash site's 6-mile radius.
The personal belongings -- luggage, clothes, toys, books -- found at the crash site so far have been collected under four tents. One pile was taken to the train station in nearby Torez, but was left on the platform when the train carrying the bodies departed abruptly on Monday for Kharkiv.
The train was met in Kharkiv by police forensic experts as well as representatives of countries whose citizens were aboard the ill-fated plane.
Under mounting world pressure, pro-Russian rebels also handed over data-filled "black boxes" from the Boeing 777 to Malaysian officials.
A senior separatist leader, Aleksander Borodai, gave the data recorders to a Malaysian delegation early Tuesday in the city of Donetsk, a rebel stronghold.
"Here they are, the black boxes," Borodai said at the headquarters of his self-proclaimed Donetsk People's Republic, Reuters reported.
Col. Mohamed Sakri of the Malaysian National Security Council told the meeting the two black boxes were "in good condition."
On Monday, the U.N. Security Council passed a resolution unanimously calling for an international investigation into the downing of the Malaysian plane.
Contributing: Filip Warwick in Torez, Ukraine, William Welch in Los Angeles; The Associated Press