A pro-Russian rebel leader in eastern Ukraine has claimed insurgents were made available, probably by Moscow - a surface-to-air missile system like the West alleges was used to shoot down Malaysia Airlines flight MH17.

Alexander Khodakovsky, commander of the Vostok Battalion, told Reuters other rebel units did possess a Russian-made SA-11 BUK missile system.

"I knew that a BUK came from Luhansk. At the time I was told that a BUK from Luhansk was coming under the flag of the LNR," he said, referring to the Luhansk People's Republic, a rebel group.

Khodakovsky suggested the missile system had probably come from Russia and was smuggled back across the border after MH17 was shot down.

"Russia could have offered this BUK under some entirely local initiative," he said. "I want a BUK and if someone offered me one, I wouldn't turn it down.

"But I wouldn't use it against something that did not threaten me. They probably sent it back in order to remove proof of its presence."

Khodakovsky also claimed Kiev knew rebels had put their hands on a BUK system but deliberately decided not to take action to provoke a tragedy.

"The question is this: Ukraine received timely evidence that the volunteers have this technology, through the fault of Russia," he said. "It not only did nothing to protect security but provoked the use of this type of weapon against a plane that was flying with peaceful civilians.

"That day, they were intensively flying and exactly at the moment of the shooting, at the moment the civilian plane flew overhead, they launched air strikes. Even if there was a BUK, and even if the BUK was used, Ukraine did everything to ensure that a civilian aircraft was shot down.

"I am an interested party. I am a 'terrorist', a 'separatist', a volunteer... In any event, I am required to promote the side I represent, even if I might think otherwise, say otherwise or have an alternative view. This causes real discomfort to my soul."

Other rebels groups and the Kremlin have denied any involvement in the downing of MH17.