The US secretary of state, John Kerry, has said all the evidence surrounding the downed Malaysia Airlines flight MH17 points towards pro-Russia separatists in eastern Ukraine being to blame. He spoke out as bodies of victims were moved by rebels on to trains several miles from the crash site.

Kerry appeared on all five major US Sunday talkshows to lay out the Obama administration's case against the separatists and to call on Russia to act and stop them from blocking an investigation into the firing of a surface-to-air missile that brought down the plane on Thursday, claiming 298 lives.

"We have enormous input about this that points fingers," Kerry told CNN's State of the Union. "It is pretty clear that this was a system from Russia, transferred to separatists. We know with confidence that the Ukrainians did not have such a system anywhere near the vicinity at that point of time."

He said the US knew that in the last month there had been a "major flow of arms and weapons from Russia to the eastern part of Ukraine and turned over to the separatists".

Kerry said social media reports and US surveillance put the missile system in question in the vicinity of the crash before the tragedy.

"We know because we observed it by imagery that at the moment of the shootdown we detected a launch from that area," he said. "Our trajectory shows that it went to the aircraft.

"We also know to a certainty that social media immediately afterwards saw reports of separatists bragging about knocking down a plane and then the so-called defence minister of Donetsk, Igor Strelkov, posted a report bragging about the shoot-down of a transport plane."

The case against the separatists was further backed by evidence from voice intercepts and a video of a launcher moving back into Russia with at least one missing missile, said Kerry.

Kerry called on Russia to "step up publicly and join in the effort to make sure there is a full fledged investigation".

Last week, the Russian foreign minister, Sergei Lavrov, said the US president, Barack Obama, should "stop lecturing Russia".

Kerry said he had spoken to Lavrov on Saturday. "It was a direct and tough conversation," he said.

Dianne Feinstein, chairman of the Senate select committee on intelligence, told CNN the type of equipment Russia had supplied to the separatists should only go to someone with "an ethical compass".

"Now we find out it's been given to separatists who are in many respects thugs. And it's been used in a very terrible way."

"The nexus between Russia and the separatists has been established very clearly," Feinstein added. "So the issue is, where is [the Russian president, Vladimir] Putin? I would say: 'Putin, you have to man up. You have to say this was a mistake,' which I hope it was."

Putin has urged the pro-Moscow rebels in eastern Ukraine to cooperate and insisted that an international investigation must not leap to conclusions. Moscow denies involvement and has pointed the finger at Kiev's military.

Ukraine and its western allies accuse Moscow of fuelling a pro-Russia uprising that threatens to break up the former Soviet republic of 46 million people. Russia denies orchestrating the unrest and says Ukraine's attempts to end it by military force are making the situation worse.

On Sunday, the bodies of the victims were loaded on to three railway carriages, apparently with refrigerator capability, standing at the train station in the town of Torez, several miles from the crash site in the Donetsk region of eastern Ukraine.

The Guardian witnessed the arrival of a delegation from the international monitoring body the Organisation for Security and Cooperation in Europe (OSCE) at around midday local time on Sunday to inspect the wagons, accompanied by a convoy of heavily armed and nervous rebels.

As they opened the metal door to one of the carriages to inspect the interior, a stench of death wafted out, and black body bags were visible inside.

"The special monitoring mission in its third day dealing with the incident has now monitored the location where bodies are being refrigerated in three wagons," said Alexander Hug, the deputy chief of the mission.

"We have not been able to count them as that would be too difficult in this situation."

Michael Bociurkiw, the spokesman for the mission, added: "Going inside the wagons is impossible without special equipment. The stench is very, very bad."

The OSCE, which has had its access to the crash site itself limited in recent days, left in a convoy to return to the crash site.

There have been no international investigators at the scene. Ukrainian authorities say they are setting up facilities for relatives to stay and autopsies in the city of Kharkiv, about 200 miles away.

Armed separatists at the scene refused to say how many bodies were in the train carriages or when they would leave. The train driver told the Guardian he had no idea of the train's destination.

The local department of Ukraine's emergencies ministry in the eastern Donetsk region said on Sunday that 196 bodies had been found at the site where the Malaysian airliner crashed.

"As of 7am on 20 July, in the Shakhtarsky region of the crash site of the Boeing 777, 196 bodies were found," it said in a statement, adding that divers were involved in the search because the area included a reservoir.

It also emerged on Sunday that the UN security council was considering a draft resolution to condemn the "shooting down" of a Malaysian passenger plane in Ukraine, demand armed groups grant access to the crash site, and call on states in the region to cooperate with an international investigation.

Australia – which lost 28 citizens – circulated a draft text, seen by Reuters, to the 15-member security council late on Saturday, and diplomats, speaking on condition of anonymity, said it could be put to a vote as early as Monday.

The draft resolution "demands that those responsible for this incident be held to account and that all states cooperate fully with efforts to establish accountability".

It "condemns in the strongest terms the shooting down Malaysia Airlines flight MH17 … resulting in the tragic loss of 298 lives" and "demands that all states and other actors in the region refrain from acts of violence directed against civilian aircraft."

Russia's UN mission declined to comment on the draft security council resolution.