The Ukraine Security Service (SBU) has released what it says is a recording of a telephone conversation between pro-Russian separatists in which they admit shooting down the Malaysia Airlines plane.
Igor Bezler, a pro-Russian rebel leader, initially reports to Vasili Geranin that "cossacks" have shot down a plane.
Ukraine alleges that Geranin is a Russian intelligence agent.
In another conversation between an alleged cossack militant and his commander, the pair realise that what they had thought was a "Ukrainian cargo plane" actually had "Malaysia Airlines" written on it.
"What was it doing over the territory of Ukraine?" the militant asks.
"Well then it was bringing spies," his alleged commander says.
"Why were they flying here? This is war going on."
Thousands of online users have taken to social media to call for the victims of the Malaysian airliner crash to be returned to loved ones.
United States intelligence officials admitted that they do not know who fired the surface-to-air missile that downed flight MH17.
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