Relatives of those killed in the MH17 air disaster are demanding the release of what they say is key evidence that could shed light on the tragedy over eastern Ukraine in July 2014.
Malaysia Airlines flight MH17 was shot down over the eastern Ukrainian region of Donetsk with the loss of all 298 lives on board, most of them Dutch.
The Dutch Safety Board said in its final report released on October 13 that the jet was destroyed by a Russian-made surface-to-air missile, fired from an area at the time under the control of pro-Russia separatists.
A separate criminal probe is also being conducted in the Netherlands to determine who was responsible and bring them to justice.
Now, Dutch relatives of the MH17 tragedy have written to Dutch Prime Minister Mark Rutte to protest that primary radar data was not made available to the investigators by either the Russian or Ukrainian authorities.
"We can't accept that people have refused to provide crucial information," the families said in the letter, published on January 13.
They are urging Rutte to push either the United Nations or the International Civil Aviation Organization to demand that the data is handed over.
The families hope that may help pinpoint who fired the missile at the plane.
The EU, the United States, and Ukraine believe the plane was downed by Russia-backed separatists using a Buk missile system provided by the Russian military.
Moscow denies providing such equipment and has suggested that the aircraft was shot down by a Ukrainian fighter jet or with a Buk fired by the Ukrainian military -- claims roundly dismissed by Kyiv and Western governments.