MOSCOW -- A Russian state-controlled missile-maker says its own investigation of last year's crash of the MH17 airliner over rebel-held eastern Ukraine contradicts conclusions of a Dutch probe.

Results of the Dutch investigation are to be released later Tuesday.

Yan Novikov, head of the Russian Almaz-Antey concern, speaking at a news conference, did not specify what was in the report and he did not say whether he had been given an advance look.

The Malaysian airliner crashed July 17, 2014, in rebel-controlled eastern Ukraine and is widely believed to have been shot down by a surface-to-air missile. Ukraine and Western countries contend the missile was fired by Russian troops or Russian-backed separatists.

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The respected Dutch daily newspaper Volkskrant quotes three sources close to the Dutch probe as saying international investigators have concluded the airliner was shot down by a Russian-made BUK surface-to-air missile fired from rebel-held eastern Ukraine, according to the French news agency Agence France-Presse.

A U.S. official told The Associated Press the draft report said the plane was destroyed by a Russian-made Buk surface-to-air missile fired from the village of Snizhne, which was under rebel control. The official, who wasn't authorized to comment publicly, spoke on condition of anonymity.

Many reports, including an investigation by the open-source group Bellingcat, also suggest the plane was downed by a missile fired from near Snizhne.

An Associated Press journalist saw a Buk missile system in the area on the same day the airliner went down. That narrative meshes with AP findings in the hours before the downing.

The Ukraine and Western allegations have focused on the Russian-made Buk missile system, which has several variants.

Almaz-Antey had said in June that a preliminary investigation suggested that the plane was downed by a model of Buk that is no longer in service with the Russian military.

However, Novikov on Tuesday hedged on that conclusion, suggesting it could have been a model even older than previously believed.

He said an experiment was conducted in July in which a missile was fired at aluminum sheets mimicking an airliner's fuselage and that shrapnel from that firing indicated an older missile model. That information was presented to the Dutch investigators, but was not taken into account, he claimed.

Almaz-Antey then conducted a "natural experiment" using a decommissioned Ilyushin-86 airliner, which Novikov said is similar to the B-777. Novikov said evidence shows that if the plane was hit by a Buk, it was fired from the village of Zaroshenske, which Russia says was under Ukrainian government control at the time.