HRABOVE, Ukraine - World leaders demanded an international investigation into the shooting down of a Malaysian airliner with 298 people on board over eastern Ukraine in a tragedy that could mark a pivotal moment in the worst crisis between Russia and the West since the Cold War.
One US official said Washington strongly suspected the Malaysian Airlines Boeing 777 was downed by a sophisticated surface-to-air missile fired by Ukrainian separatists backed by Moscow.
There were no survivors from Thursday's crash, which left wreckage and bodies scattered across miles of rebel-held territory near Ukraine's border with Russia.
The scale of the disaster could prove a turning point for international pressure to resolve the crisis in Ukraine, which has killed hundreds since protests toppled the Moscow-backed president in Kiev in February and Russia annexed the Crimea a month later.
While the West has imposed sanctions on Russia over Ukraine, the United States has been more aggressive than the European Union in this respect. Analysts believe the response of Germany and other European powers to the incident could be crucial in deciding the next phase of the stand-off with Moscow.
The United States called for an immediate ceasefire to allow easy access to the crash site, while pro-Russian separatists told the Organisation for Security and Co-operation in Europe (OSCE), a security and rights body, they would ensure safe access for international experts visiting the scene.
The plane crashed about 40km from the border with Russia near the regional capital of Donetsk, an area that is a stronghold of rebels who have been fighting Ukrainian government forces.
Leaders of the rebels' self-proclaimed Donetsk People's Republic denied any involvement and said a Ukrainian air force jet had brought down the intercontinental flight.
Ukraine on Friday closed the air space over the east of the country.
The plane's two black boxes - voice and data recorders - were recovered, but since the crash site was in rebel hands it was unclear who would analyse them and whether they could shed light on the crucial question of who fired the missile.
Further complicating any investigation, local people were seen removing pieces of wreckage as souvenirs. The condition of the metal can indicate if it has been struck by a missile.
Reuters journalists saw burning and charred wreckage bearing the red and blue Malaysia Airlines insignia and dozens of bodies in fields near the village of Hrabove.
Makeshift white flags marked where bodies lay in corn fields and among the wreckage.
An emergency worker said at least 100 bodies had been found so far and that debris was spread over 15km. The airline said it was carrying 283 passengers and 15 crew.
"I was working in the field on my tractor when I heard the sound of a plane and then a bang," one local man told Reuters at Hrabove, known in Russian as Grabovo. "Then I saw the plane hit the ground and break in two. There was thick black smoke." US Vice President Joe Biden said it appeared the downing of the jetliner was not an accident and that it apparently was "blown out of the sky".
"While we do not yet have all the facts, we do know that this incident occurred in the context of a crisis in Ukraine that is fuelled by Russian support for the separatists, including through arms, materiel, and training," White House spokesman Josh Earnest said in a statement.
The Ukrainian government released recordings it said were of Russian intelligence officers discussing the shooting down of a civilian airliner by rebels who may have mistaken it for a Ukrainian military plane.
Most of the dead, 173 people, were Dutch. Twenty-eight were Malaysian, 28 Australian, 12 Indonesian, nine British, four German, four Belgian, three Filipino and one each from Canada and New Zealand. All 15 crew were Malaysian. Nationalities of the others aboard were unclear.
A number of those on board were travelling to an international AIDS conference in Melbourne, including Joep Lange, an influential Dutch expert.