Ukraine's security service has released what it said was an intercepted telephone conversation in which a rebel leader admitted to shooting down Malaysia Airlines MH17, reports said.

The recording, which was released with a transcript on YouTube, purports to be between Igor Bezler, the commander of rebel forces in the town of Horlivka, and a man identified as Vasili Geranin, a colonel in Russia's GRU military intelligence agency, London Telegraph reported.

Speaking in Russian, the voice identified as Bezler's informs "Geranin" that an aircraft has been shot down and that a team has been sent to inspect the wreckage and search for survivors.

Later, two other men - using the noms de guerre "Major" and "Greek" - are heard discussing the discovery that a "100 per cent civilian" aircraft was shot down.

"I'm only where the first bodies fell," Major tells Greek. "F***, the debris fell right in people's gardens. There are civilian things - medicine, towels, toilet paper."

"Are there any documents?" asks Greek

"Yes," says Major "of one Indonesian student."

The conversation appears to back up the Ukrainian version of events - that either the rebels themselves or the Russians fired the missile that destroyed the Malaysian Airlines aircraft.

But while the conversation sounds plausible, it is impossible to verify, Telegraph reported.

Mr Bezler, who goes by the nom-de-guerre "Bes," is a well known rebel commander in Eastern Ukraine and operates out of Horlivka, not far from the crash site, the identifies of "Major," "Greek," and even "Geranin" are less clear.