Malaysia must move forward towards ensuring that those responsible for the downing of Malaysia Airlines Flight MH17 are held accountable for the murderous act, said Prime Minister Datuk Seri Najib Tun Razak.

He said as the investigation by the Dutch Safety Board had revealed that the plane was hit by a Russian-made Buk missile fired from rebel-held territory in eastern Ukraine, the on-going criminal investigation must provide definitive answers and allow Malaysia to pursue the strongest action possible against those responsible.

"The on-going criminal investigation, which is being led by the Dutch with our full support, must provide definitive answers and allow us to pursue the strongest action possible against those responsible," he said in a statement here, tonight.

He added that he had earlier today spoken to Dutch Prime Minister Mark Rutte, Australian Prime Minister Malcolm Turnbull and the Dutch Safety Board, ahead of their long awaited report on the shooting down of flight MH17.

Najib said the ill-fated event was an unforeseeable act and, of the 160 flights that were on MH17's general route that day, not one was advised by the relevant authorities against any specific threat.

"Fifteen months may have passed, but our commitment to bringing the perpetrators to justice remains as strong as it was on that fateful day, July 17, 2014, when hundreds of innocent people lost their lives in a conflict that was not theirs," he said.

A total of 298 lives were lost on that tragic day. Forty-three of them were Malaysians.

Najib said that many of the victims relatives were also present in The Netherlands today, where they were briefed on the findings of the report.

"It has been, and will remain, a difficult journey – particularly for those who lost their loves ones, who are in my thoughts and prayers," he added.

READ: MH17: Malaysia remains committed in persuing decisive action