International investigators will on Tuesday release their final report into the shooting down of Malaysia Airlines flight MH17 over war-torn Ukraine, but the burning question of who was to blame will remain unresolved.

The Dutch Safety Board (OVV), leading a team of international investigators since the Boeing 777 went down last year, will release the report at 1115 GMT at the Gilze-Rijen air force base in southern Netherlands.

All 298 people on board - most of them Dutch - including the 15 crew members died when the routine flight between Amsterdam and Kuala Lumpur was brought down, possibly by a missile, during heavy fighting between Ukrainian forces and pro-Russian separatists.

Tuesday's report - 15 months after the July 17, 2014 crash - will focus on four subjects, the Dutch board said in a statement.

"The cause of the crash; the issue of flying over conflict areas; the question why Dutch ... relatives of victims had to wait two to four days before receiving confirmation from the Dutch authorities that their loved ones were on board; and lastly, the question as to what extent the occupants of flight MH17 were conscious of the crash."

But as the board has pointed out many times, it will not assign blame nor say who pulled the trigger.

"It is the purpose of the criminal investigation to answer those [questions]," it said.

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