Flowers and mementos left by local residents at the crash site of the Malaysia Airlines Flight MH17 are seen near the settlement of Rozspyne in the Donetsk region, in this July 19, 2014 fie photo. REUTERS/Maxim Zmeyev/Files

VINNYTSIA, Ukraine (Reuters) - A former top official in Ukraine’s security service said on Friday he doubted a final international report on the crash of Malaysian Airlines flight MH17 would provide conclusive answers.

The Dutch Safety Board report, to be published on Oct. 13, is keenly awaited by governments and relatives of victims who hope it can shed light on responsibility for the crash over east Ukraine last year in which 298 people were killed.

Vasyl Vovk, who was involved in investigating the crash as chief investigator for Ukraine’s SBU security service until June this year, said it was clear the plane was shot down by a Russian missile on behalf of pro-Russian separatist rebels

“I am confident that this missile system was delivered from the territory of the Russian Federation with a high-skilled crew - most likely a crew of well-trained officers, of course from Russian territory,” he told Reuters.

However Vovk said he doubted whether the Oct. 13 report would reach the same conclusion.

“I have doubts that we will see these conclusions on Oct. 13 ... And if we see them, then I doubt that these conclusions will be either unambiguous or final,” he said.

In a preliminary report last year, the Board blamed the crash on “high energy objects” striking the aircraft. Western governments have said they believe it was downed by a ground-to-air missile fired in error by Moscow-backed separatists.

Russia contests that claim, and has variously attributed the crash to an unidentified Ukrainian fighter aircraft and a Ukrainian-launched anti-aircraft missile. The Netherlands has avoided committing itself to any theory.

Two-thirds of the victims were Dutch and the Netherlands is leading the judicial and air safety investigations into the crash, which contributed to bringing relations between Russia and the West to their lowest ebb since the Cold War.