Russia is defying international pressure to drop its support for separatists in eastern Ukraine following the shooting down of a Malaysia Airlines passenger jet – instead advancing its own narrative suggesting the rebels may be innocent and laying blame for the tragedy on the Ukrainian military.

Canada announced a fresh round of sanctions against Russia on Monday, and U.S. President Barack Obama called for Moscow to "pivot away" from the insurgency in Ukraine. But Russian President Vladimir Putin showed no signs of blinking. The Kremlin made a point of announcing that Mr. Putin will convene his Security Council, which includes Russia's military chiefs, on Tuesday.

It's not clear what security issues he has in mind, but the meeting seems likely to involve Moscow's relationship with the eastern Ukrainian rebels. Russia's defence ministry, meanwhile, rolled out an elaborate alternative theory that suggested a Ukrainian fighter plane had played a role in the downing of Flight MH17 and the deaths of all 298 people on board.

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In a rare sign of co-operation, the UN Security Council, where Russia sits as a permanent member, passed a unanimous resolution calling for immediate access to the crash site, and for the repatriation of the victims' remains. There were also signs of progress on the ground: The rebels handed the "black box" flight recorders over to a Malaysian delegation, and a train loaded with 282 recovered bodies was finally allowed to leave the rebel-controlled area, headed toward the government-controlled city of Kharkiv and a waiting plane to move the remains to the Netherlands.

But as soon as the UN resolution was passed, the U.S., Australian and British ambassadors slammed Russia for not having acted fast enough to secure the crash site. "Russia's silence since Thursday sent a message to the illegal armed groups it supports: We have your backs," Samantha Power, the U.S. envoy to the UN, said.

Russian ambassador Vitaliy Churkin lashed back angrily, accusing the U.S. and its allies of playing politics with a tragedy.

Earlier Monday, Russia's defence ministry unveiled what it said was evidence that a Ukrainian Su-25 fighter jet had approached the Malaysia Airlines Boeing 777 shortly before the passenger plane exploded on Thursday.

"Records show that the Ukrainian Air Force plane ascended to the distance of three to five kilometres from the Malaysian Boeing," said Lieutenant-General Andrei Kartapolov, head of the main operations directorate of the Russian Army's General Staff. He produced what he said were video grabs from a Russian radar station in the city of Rostov, near the country's border with Ukraine, that appear to show a second contact in close proximity to the Malaysian plane just before MH17 was knocked out of the air.

"We would like Kiev to explain why a combat jet was flying almost at the same altitude and the same time with a passenger plane along the route dedicated for civilian air traffic," he said.

Lt.-Gen. Kartapolov said the Su-25 was within firing range of MH17, but it wasn't clear whether he was alleging the Ukrainian fighter had shot down the passenger plane or whether he was suggesting its presence explained why someone on the ground might have accidentally targeted the passenger plane.

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Ukrainian President Petro Poroshenko, who has called the downing of MH17 an act of "terrorism," said the Russian allegation simply wasn't true. "Everybody knows that in this period of time when the tragedy happened all Ukrainian planes were on the ground [in the area]," Mr. Poroshenko told CNN.

Russia's alternative version of events likely won't change many minds in the West. U.S. Secretary of State John Kerry declared on Sunday that "we know with confidence" that it was an SA-11 surface-to-air missile that hit the passenger plane, and that the missile was fired from a rebel-controlled part of eastern Ukraine. U.S. officials have accused Russia of providing such missiles – and well as training on the Soviet-era antiaircraft systems required to target and fire them – to the rebels, who have been fighting central government forces since April. The self-proclaimed Donetsk People's Republic rejects Ukraine's pro-Western government, and seeks eventual union with Russia.

On Monday, Mr. Obama accused the pro-Russian separatists of intentionally keeping international investigators away from the site of the plane crash, which came down in rebel-held territory near the village of Grabovo in eastern Ukraine. "What are they trying to hide?" Mr. Obama asked.

Foreign Minister John Baird was also dismissive of the Russian military's presentation. "I'm … very leery of any propaganda coming out of the Kremlin," he said in London after announcing Canada would expand the list of Russian individuals and companies targeted for sanctions. Mr. Baird said that if Russia wanted the world to consider its evidence, it "should be strongly and aggressively supporting securing the [crash] site."

Mr. Baird said he hoped European countries would take a tougher line toward Moscow. European Union foreign ministers are due to meet Tuesday to discuss new sanctions against Russia, in addition to those it has imposed since Russia annexed Crimea in March.

A furious Prime Minister Mark Rutte of the Netherlands, whose citizens accounted for the majority of the MH17 casualties, told his country's parliament that "all political, economic and financial options" were open if Russia didn't assist in securing rapid access for investigators to the crash site.

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A Dutch-led team of forensics experts reached the rebel-held area Monday, four days after the disaster, and was allowed to see the refrigerated rail cars where bodies from the crash site were being stored. Larger teams of specialized investigators from the Netherlands, Malaysia and the United Kingdom have also arrived in Ukraine, but the Ukrainian government said Monday it was still unable to guarantee them safe passage.

Dutch Foreign Minister Frans Timmermans expressed outrage over delays in dealing with the crash victims. "Until the day I die I will not understand how it is possible that it would take us days to get an act of human decency together which is simply to be able to gather the remains in a respectful way, bring them to a morgue and bring them back home," he told reporters in New York.

Fighting meanwhile intensified in eastern Ukraine, with shells landing near the railway station in the city of Donetsk. A Donetsk People's Republic source told The Globe and Mail that the Ukrainian military had targeted the railway station with Grad rockets, and that at least three people had been killed. Another Donetsk resident said that he saw two bodies near the train station, but that he believed the incoming rounds had been fired from a rebel-held area near the city.