Russia is facing international calls to accept responsibility for the downing of flight MH17 over eastern Ukraine in 2014, which caused the deaths of all 298 people onboard.
Australia and the Netherlands on Friday accused Moscow of complicity in the incident, while Britain’s foreign secretary, Boris Johnson, said the Kremlin “must now answer for its actions”.
“The Kremlin believes it can act with impunity. The Russian government must now answer for its actions in relation to the downing of MH17,” said Johnson in a statement.
A Downing Street spokesman said that during a phone call with Ukraine’s president, Petro Poroshenko, Theresa May said the allegations “fit into a well-established pattern of Russian aggression”.
Despite longstanding suspicion and a mounting body of evidence pointing to Russia’s involvement, this is the first time governments have officially accused Moscow over the incident.
“Australia and the Netherlands have now informed the Russian Federation that we hold it responsible under international law for its role in the bringing down of MH17,” said Australia’s foreign minister, Julie Bishop, on Friday.
She called on Russia to “enter into negotiations to open up a dialogue about its conduct and to seek reparations”.
The call is likely to bring about a diplomatic standoff, with Russia continuing to deny complicity and refusing to cooperate with investigators.
On Thursday a team of international investigators said they had hard evidence that the missile system involved in shooting down the Malaysia Airlines plane came from a Russian military brigade.
The plane, which was flying from Amsterdam to Kuala Lumpur, was shot down over the conflict zone in eastern Ukraine in July 2014. More than half of the victims were Dutch, and there were also 44 Malaysians and 28 Australians on board.
Bishop said her country would seek financial compensation from Russia for the families of the Australians. “They want to see closure but they also deserve justice and we will be seeking reparations for the atrocities caused by this conduct,” she said.
Johnson said the MH17 incident was “an egregious example of the Kremlin’s disregard for innocent life” and he offered his support for the Dutch and Australian demands.
“The UK fully supports Australia and the Netherlands in their request to the Russian Federation to accept state responsibility and to cooperate with them in their efforts to deliver justice for the victims of this tragedy,” he said.
The EU and Nato also issued statements calling on Russia to accept responsibility.
Witnesses on the ground at the time said they had seen a Buk missile system travel through separatist-controlled areas of eastern Ukraine on the day of the downing, while a variety of photo and video evidence has pointed to a Buk system that crossed from Russia.
On Thursday the Joint Investigation Team (JIT) said it had “legal and convincing evidence which will stand up in a courtroom” that the missile system came from Russia’s 53rd anti-aircraft missile brigade, based in the western city of Kursk.
Russia has vetoed a UN tribunal to determine guilt for the incident, so the JIT intends to issue indictments for a trial to be held in a Dutch court. On Thursday the Dutch chief prosecutor, Fred Westerbeke, said the investigation was now in its “last phase” but he declined to say when a court case might start.
He said the JIT was investigating “several dozen” suspects for complicity in the incident, though he did not say how high up the chain of command they went.
Russia has issued a series of blanket denials over involvement, and officials and state-linked media have floated a series of implausible alternative theories suggesting the Ukrainian armed forces were to blame.
On Friday the Russian defence ministry issued a fresh statement suggesting all Buk missiles with the serial numbers indicated by the JIT had been destroyed in Russia in 2011, suggesting the missile must have come from the Ukrainian armed forces.