Russian arms manufacturer Almaz Antey claims that an older version of the Buk surface-to-air missile found in Ukrainian but not Russian military arsenals downed flight MH17 over east Ukraine.
Mikhail Malyshevsky, adviser to the director general of the state-owned arms consortium, said that the conclusion had been formed by company experts after studying photographs of debris from the crash site.
The plane was downed in July 2014, killing all 298 people on board.
The West accused militias battling Ukrainian government forces in east Ukraine of downing the plane used a Buk missile provided by the Russian military.
Moscow denies the allegations, and has accused Ukrainian forces of shooting down the Malaysian Airlines plane, which was flying from Amsterdam to Kuala Lumpur.
In October, German intelligence claimed that the plane was shot down by pro-Russian militias using a Buk seized from Ukrainian forces.
Almaz Antey was subjected to Western economic sanctions in the wake of the incident.
Malyshevsky claimed evidence indicated that damage to the plane had been caused by a type of shrapnel only found in the older model Buk used by the Ukrainian military.
He said that the missile was not launched from Snizhne, as Kiev alleges, but from another part of territory held by pro-Russian militants.
Most of the passengers killed in MH17 were Dutch, and the Dutch Safety Board is conducting an investigation into the incident, with its reports to be published in October.