The Netherlands and Australia have announced they are holding Russia legally responsible for its role in the downing of a Malaysian passenger jet over Ukraine nearly four years ago.

The move puts further strain on already tense relations between Moscow and the West and opens a new legal front in the long-running process of apportioning blame for the July 17 2014 missile strike that blew Malaysia Airlines Flight 17 out of the sky and killed all 298 people on board.

“State responsibility comes into play when states fail to uphold provisions of international law and that’s clearly the case,” Dutch prime minister Mark Rutte told reporters, a day after international prosecutors said they had unequivocal evidence of Russian involvement.

On Thursday, a Dutch-led international team of investigators said they had strong evidence that the Buk missile system that brought down the Amsterdam-Kuala Lumpur flight came from a Russia-based military unit, the 53rd anti-aircraft missile brigade based in the Russian city of Kursk.

It was the most explicit link yet published by the investigators between Moscow and the downing of Flight MH17.

Australian foreign minister Julie Bishop called for international support for the Dutch-Australian legal initiative.

“If military weapons can be deployed and then used to bring down civilian aircraft in what was essentially a war zone, then international security is at risk and we call on all countries to inform the Russian Federation that its conduct is unacceptable,” she said.

The two nations quickly got support from allies including the US, UK and the European Union.

“It is time for Russia to acknowledge its role in the shooting down of MH17 and to cease its callous disinformation campaign,” US State Department spokeswoman Heather Nauert said.

British Foreign Secretary Boris Johnson called Russia’s involvement “an egregious example of the Kremlin’s disregard for innocent life” and called on Moscow to co-operate fully with the investigation.

Russia denies involvement in the downing of the Boeing 777 that was flying 33,000ft over war-ravaged eastern Ukraine when it was torn apart by a missile fired from territory controlled by pro-Russian rebels.

Bodies, debris and burning wreckage rained out of the sky into a field of sunflowers near the rebel-held village of Hrabove in the Donetsk region, about 25 miles from the Russian border, where fighting had been raging for months.

Russian President Vladimir Putin denied Russia was responsible for downing MH17.

He said the Ukrainian military could have been responsible, noting a 2001 incident in which the Ukrainian army accidentally downed a Russian airliner over the Black Sea, killing all 78 people on board.

He said Moscow would not trust the investigation’s final findings because Russia is excluded from the investigative team.

“We aren’t taking part in it, and our arguments haven’t been accepted by the investigative commission,” he said.

Russian foreign minister Sergey Lavrov told reporters that Moscow has co-operated with the criminal probe and sent data including radar images from the day the plane was shot down.

“The foreign minister of the Netherlands called me to say they have no doubts that the Buk came from Russia,” Mr Lavrov said.

“I asked him about the facts that would prove it, but he failed to offer any. He said they want Russia to help determine the facts on the basis of those unfounded claims.”

Relatives of those killed welcomed developments over the last two days as the fourth anniversary of losing their loved ones approaches.

“This is great news,” said Hans de Borst, who lost his daughter Elsemiek. “I understand why the government waited, but now the evidence is clear.”

Silene Fredriksz-Hoogzand, whose son Bryce and his girlfriend were on board the flight, called the investigation’s findings an important step forward and the decision to hold Russia responsible “two steps forward”.