London: Ukraine's Prime Minister has said those guilty for the downing of MH17 must be punished, despite sending a key witness to Russia, putting him out of reach of international investigators who will try four men over the downing of the plane in 2014.

Ukraine exchanged 58-year old Volodymyr Tsemakh in a mass prisoner swap with Russia in September as part of the new government's attempts to end the long-running feud between the two countries.

Ukrainian filmmaker Oleg Sentsov, who was recently awarded in London, was among 35 prisoners freed by Russia in return.

A file photo shows the wreckage of the MH17 near the village of Grabovo, Ukraine. 298 people lost their lives. Credit:AFP

Asked by The Sydney Morning Herald and The Age to explain to the victims of MH17, why the Tsemakh was returned to Russia, out of the reach of Dutch prosecutors, Ukraine's Prime Minister Oleksiy Honcharuk blamed Russia for the shooting down of the Malaysia Airlines plane.