US officials claim they have evidence of a Russian plan to make a “very graphic” fake video of a Ukrainian attack as a pretext for an invasion. The alleged plot would involve using corpses, footage of blown-up buildings, fake Ukrainian military hardware, Turkish-made drones and actors playing the part of Russian-speaking mourners. “We don’t know definitively that this is the route they are going to take, but we know that this is an option under consideration,” the deputy national security adviser, Jonathan Finer, told MSNBC, adding that the video “would involve actors playing mourners for people who are killed in an event that they would have created themselves”. Finer added: “That would involve the deployment of corpses to represent bodies purportedly killed, of people purportedly killed in an incident like this.” The Pentagon spokesman, John Kirby, said the video would have purported to show a Ukrainian attack on Russian territory or Russian-speaking people in eastern Ukraine and would be “very graphic”. He added that the US believed that the plan had the backing of the Kremlin. “Our experience is that very little of this nature is not approved at the highest levels of the Russian government,” Kirby said. US officials said the video would show Turkish-made Bayraktar drones taking part in the fabricated attack as a way of implicating Nato. The claims are being made in the midst of a war of nerves between Russia and the US and its allies, in which diplomatic exchanges and intelligence briefings are playing out alongside a relentless Russian military buildup around Ukraine’s borders, and US and allied threats of devastating punitive economic measures if an attack goes ahead. Administration officials said the plan was to use the video as evidence of Ukrainian “genocide” against Russian speakers to justify Russian military intervention. By going public, the US hoped to stall or slow down Moscow’s plans. Finer said it would “make it much more difficult for them after the fact to claim that they had to do whatever they decided to do”. The New York Times and Washington Post first published versions of the account given by administration officials, noting that the officials did not provide evidence for the US claims. Britain said it agreed with the US assessment, having conducted its own analysis of the intelligence reports. The two countries routinely share intelligence as part of the wider Five Eyes network – and London has been as ready as Washington to highlight what both see as an acute Russian threat to Ukraine. Liz Truss, the foreign secretary, said the disclosures were “clear and shocking evidence of Russia’s unprovoked aggression and underhand activity to destabilise Ukraine”. She added: “The UK and our allies will continue to expose Russian subterfuge and propaganda and call it out for what it is.” The US and UK have alleged that Russia has deployed operatives inside Ukraine to stage false-flag attacks and has recruited Ukrainians to take over a puppet government that would collaborate with Russian occupation forces. James Roscoe, a British diplomat at the United Nations said: “Russia says it will never invade Ukraine. Unless it is provoked. So ‘just in case’ it is provoked it has massed over 100,000 troops on Ukraine’s border. “But how is it that they are able to anticipation that provocation?” Roscoe asked on Twitter. “Perhaps because they are planning to stage that provocation?” While massing troops around Ukraine, Russian officials have made repeated claims, without evidence, that Kyiv was planning to attack Russia or Russian speakers in eastern Ukraine rather than the other way round. Last week, a Moscow-backed separatist leader in eastern Ukraine, Denis Pushilin, repeated a frequent Russian claim that Ukraine had plans to launch a chemical attack on the breakaway region. Thursday’s claims were the latest in a series of US briefings on American intelligence assessments, some of which have irritated Ukraine’s leadership and been rebuffed by officials in Kyiv. Last weekend, Reuters and CNN cited senior US officials claiming Russia had moved blood supplies close to the border, indicating a potential imminent military attack. Ukraine’s deputy defence minister, Hanna Maliar, denounced the blood supply claim, calling it a provocation designed “to spread panic and fear in our society”. On Thursday, Maliar told the Guardian she had checked that claim with Ukrainian intelligence agencies, which had their own sources. “It simply wasn’t true. We found no information to back this up, we did not see any blood supplies moved to the front or even in the civilian hospitals around the front,” she said, in an interview at a military airfield at Boryspil, outside Kyiv. “It’s really important to look at the sources. These sources were anonymous, and I don’t think it’s right to use anonymous sources that cannot be checked,” she said.