GRABOVE, UKRAINE (AFP) - Ukraine on Saturday accused Russia of helping insurgents destroy evidence at the crash site of a Malaysian jet whose downing in the rebel-held east has drawn global condemnation of the Kremlin.
Outraged world leaders have demanded Russia's full cooperation with what is becoming a monumentally challenging probe into the shooting down of a Kuala Lumpur-bound flight from Amsterdam with 298 people from a dozen countries on board.
Rebels backed up by muscular diplomatic support from the Kremlin have shown few signs of being ready to cooperate with an investigation that could blame them for blowing apart the Boeing 777 jet.
International monitors were met on Saturday by Kalashnikov-wielding militias who allowed them access to only the outskirts of the field - its swaying sunflowers hiding dismembered remains of charred and decomposing bodies of victims whose lives were cut short on Thursday.
The grisly site has turned into the epicentre of the Cold War-style standoff between the West and an increasingly isolated Moscow - its diplomatic reputation questioned around the world - over the future over the war-scarred former Soviet state.
The Ukrainian government issued a furious statement declaring that the "terrorists with the support of Russia are trying to destroy proof of this international crime".
Kiev said the rebels were hours away from loading vital clues aboard trucks that would be rushed across the Russian border before a full team of experts inspected the expansive site where remains of flight MH17 hit the ground.
The explosive charges set off near-panic across global capitals on Saturday. Malaysia's transport minister expressed immediate alarm over "indications that vital evidence has not been preserved in place".
And Dutch Prime Minister Mark Rutte - his tiny nation mourning the loss of 192 compatriots - said he had called on Russian President Vladimir Putin during a "very intense" conversation to "take responsibility" for a credible probe.
Rebel leader Oleksandr Borodai told reporters that militias had never recovered the data recorders and denied tampering with any evidence. But he found the Kremlin's verbal backing eroding as the day wore on and global pressure on Putin mounted.
Moscow said in a statement released after talks between US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov that "material evidence, including black boxes" must be immediately handed over to inspectors.
The diplomatic wrangling was accompanied by uninterrupted fighting across Ukraine's eastern rustbelt - a Russia-speaking region of seven million people who largely view the more nationalistic west of the splintered country with mistrust.
Ukrainian forces reported taking full control of the main airport of the separatist stronghold of Lugansk - like Donetsk the capital of its own "People's Republic" - and launching all-out offensives against two nearby towns.
Government troops said they had also established full control of Donetsk airport for the first time since it was seized at the end of May in a bloody raid that saw militias lose more than 40 fighters - most of them Russian nationals.
Kiev said the latest clashes killed five soldiers and wounded another 20.