malaysia airlines MH17 Ukraine
Armed pro-Russian separatists stand at the site of the Malaysia Airlines Boeing 777 plane crashReuters

Pro-Russian separatists who are believed to have shot down Malaysia Airlines flight MH17 are apparently covering their tracks by obstructing European investigators at the crash site, removing internet footage of their capture of Buk missile launchers from Ukrainian government forces and deleting boastful chatter on the downing of the plane from social media platforms.

An initial team of international investigators who arrived at the miles-long crash site were driven away by the rebels who fired warning shots and curtailed access to key areas.

Although the fighters, who control the region over which the ill-fated Malaysian plane crashed, had initially offered access to search and investigation teams, they seem to have backtracked after stronger evidence linking them to the horrific death of 298 people emerged.

The Organisation for Security and Co-operation in Europe (OSCE) said its monitors had to go back from the crash site as wary rebel fighters did not allow them to set up an access corridor for specialist investigators.

"A visibly intoxicated armed guard fired his rifle in the air when one of the observers walked out of the prescribed area," OSCE team member Michael Bociurkiw said, according to BBC.

Immediately after the crash, Ukraine had said the rebels hampered the search operations.

"The search work is difficult because we are talking about a big radius ... but also because armed terrorists who are on the spot are hampering things," Serhiy Bochkovsky, the head of the head of Ukraine's emergency services, told Reuters.

According to US intelligence, the passenger plane was brought down by a surface-to-air missile. President Barack Obama and other world leaders have issued strongly worded statements condemning Russia's help for the rebels in getting hold of sophisticated weapon systems.

"These separatists have received a steady flow of support from Russia ... This includes arms and training. It includes heavy weapons, and it includes anti-aircraft weapons," Obama said.

With Russia and the Ukrainian rebels on the back foot and with international pressure growing for an impartial investigation into the tragedy, there are apparent efforts to smudge evidence.

It has been reported that the Buk battery used to launch the SA-11 missile that hit the jetliner has been moved further into the Russian side of the border.

A video released by the Ukrainian interior ministry showed a Buk missile launcher being carried in a truck towards the Russian border. The video, which could not be independently verified, showed one of the missiles was missing on the Buk launcher.

The rebel fighters and their sympathisers have deleted from social media pictures of the capture of a Buk launcher from government forces. The rebels had claimed last month that they had captured the pad, which alone can launch missiles that can hit flying objects at a cruising altitude.

The separatists also denied they posted boastful messages immediately after the Malaysian flight's crash.

A Nato intelligence analyst told defence magazine Jane's that the Russian handlers of the separatists might have asked them to cover their tracks. "It will be interesting to see if we ever find this Buk battery again or if someone now tries to dump it into a river," the analyst said.

Even as calls for independent investigation into the shooting down of the plane become louder, analysts have pointed out that the process may be far from being easy.

Difficult task

The available information on the crash is apparently rudimentary and simple. It was a surface-to-air missile that hunted the plane down, and the missile was launched from an area controlled by Russian-backed separatists. Also, Ukraine said it intercepted messages between rebel commanders discussing the shooting down of a plane.

The crash happened over a conflict zone and debris from the crash are scattered over several kilometres of farmlands. It is doubted if the flight data recorders would be of significant use in determining who exactly was responsible for the attack.

Black box

Earlier, there were reports that the rebel fighters had retrieved the black box of the plane from the crash site and that it was being sent to Moscow, raising concerns if it would ever be handed over for an impartial investigation.

Later, the Russians denied the flight data recorder was accessed by them. Russia's foreign minister Sergie Lavrov himself said the black box was not with Russia, adding that such an action would violate international laws.

However, analysts have pointed out that the black box could provide little useful information about the crash. The plane was brought down by an SA-11 radar guided missile that travelled at three times the speed of sound. The pilots might not have even seen it chasing down the plane, and the aircraft disintegrated within a fraction of a second on impact.