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An armed pro-Russian separatist stands on part of the wreckage of the Malaysia Airlines Boeing 777 plane after it crashed near the settlement of Grabovo in the Donetsk region, July 17, 2014. REUTERS/Maxim Zmeyev

A German intelligence report has alleged that pro-Russian separatists shot down Malaysia Airlines flight MH17 using an air-defence missile system seized from a Ukrainian military base.

Germany's federal intelligence service BND told a parliamentary committee that unambiguous evidence, including satellite images, suggested that MH17 was downed by a surface-to-air Buk missile fired by the insurgents.

"It was pro-Russian separatists," BND President Gerhard Schindler was quoted as saying by Spiegel magazine.

Four German nationals were among the 298 people who died, as the Boeing 777 flying from Amsterdam to Kuala Lumpur crashed over rebel-held territory in eastern Ukraine on 17 July.

Kiev and its Western allies have long accused Russian-backed rebels for the disaster. However, the BND's report differs from previous reconstructions claiming the Buk missile system was supplied to the insurgents by Moscow.

According to the federal agency's findings, which were presented to the Bundestag committee monitoring the work of German intelligence earlier in October, the separatists captured the weapon at a Ukrainian military base.

Rebels have denied any involvement, but shortly after the crash Igor "Girkin" Strelkov, a powerful pro-Russia commander, posted a statement on VKontakte, Russia's version of Facebook, taking responsibility for the attack.

"We warned them not to fly in our sky," he wrote. The post was later deleted.

The BND also said that according to its analysis, Russian claims that the aircraft was shot down by Ukraine and that a Ukrainian fighter jet was flying close to MH17 shorty before the crash were false.

A Dutch report released in September said that the aircraft broke up in mid-air after being struck by "objects" that "pierced the plane at high velocity", but stopped short of laying blame for the incident.