Russia has come under a sustained barrage of almost universal condemnation as nations lined up at the UN security council in New York to decry its role in the Salisbury chemical weapons attacks.

A day after the prime minister, Theresa May, told the UK parliament that two members of the Russian military intelligence agency, GRU, had been found to have carried out the novichok nerve agent attack in March, which poisoned the former Russian spy Sergei Skripal and his daughter Yulia, international repercussions came swiftly and decisively. Led by the UK ambassador to the UN, Karen Pierce, a host of governments turned on Moscow.

Pierce accused Russia of “playing dice with the lives of the people of Salisbury”.

“This is a direct challenge to the rules-based international system,” she said, adding that Moscow worked “in a parallel universe where the normal rules of international affairs are inverted”.

With a stony-faced Russian ambassador, Vasily Nebenzya, sitting just two seats away from her in the world chamber, Pierce went on to accuse Moscow of flouting international law in a “brazen and reckless manner”. She said: “The time for lies and recrimination has passed – it is now time for truth and accountability.”

Salisbury poisonings: police name two Russian suspects Read more

Having soaked up almost an hour of diplomatic opprobrium, Nebenzya’s response when it came was barely contained. He charged the government with putting out “repeated lies” about Russia’s development of novichok, and called the British case against the two Russian intelligence officers, known by their suspected aliases of Alexander Petrov and Ruslan Boshirov, an “unfounded and mendacious cocktail of facts”.

London’s actions, the Russian envoy told the world chamber, was motivated by “Russophobia” and intended “to unleash disgusting anti-Russian hysteria”.

The British prime minister received international support when the US, Canada, France and Germany issued a statement saying they had “full confidence” in the British assessment of Russian responsibility.

In a joint statement with the UK, the four countries said the operation to poison the Skripals was “almost certainly approved at a senior government level” and staged by the GRU, Russia’s secretive military intelligence outfit.

They urged Russia to disclose in full its novichok programme. The case against Moscow laid out on Wednesday by the UK “further strengthens our intent to continue to disrupt together the hostile activities of foreign intelligence networks on our territories”, they said. One notable European country was missing from the declaration supporting the UK: Italy.

The backing from key western allies came as officials in Moscow dismissed evidence presented by Scotland Yard and made clear they had no interest in tracking down or arresting the two suspects.

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Vladimir Putin’s long-time press spokesman, Dmitry Peskov, said Russia “has no reasons” to investigate Petrov and Boshirov – who flew from Moscow to London on genuine Russian passports – because Britain has not asked for legal assistance.

Peskov described May’s claims of Russian state involvement as “unacceptable”. He insisted that “no-one in the Russian leadership has anything to do with the poisoning”.

He added: “We again say that neither the upper leadership, nor the leadership a rank lower or any official representatives had or have anything to do with the events in Salisbury in March.”

The UK security minister, Ben Wallace, said Putin was “ultimately responsible” for the novichok attack. Wallace went further than May, who on Wednesday told MPs that the operation “was almost certainly approved at a senior level of the Russian state”.

The Kremlin’s denials are predictable. It has made similar statements before. But the compelling evidence presented by police on Thursday – including numerous CCTV images of Petrov and Boshirov visiting London and Salisbury – make Moscow’s diplomatic fightback trickier.

The Russian foreign ministry spokeswoman Maria Zakharova seized on an apparent discrepancy in images of the two alleged GRU officers released by police. Petrov and Boshirov flew in to Gatwick airport from Moscow on Friday 2 March. The photos were recorded at the same time: 16.22 and 43 seconds.

“The same place, the same corridor, and the timestamp on the footage is identical to the second,” Zakharova told Russian state TV. She accused the police of doctoring the images. Britain’s behaviour, she added, amounted to “god-level trolling” and “utter loutishness” with the case a “hellish carousel without beginning or end”.

On Thursday, Scotland Yard said the images of the two suspects were taken from two different cameras covering separate airport lanes. They were recorded at the point where passengers exit from international arrivals, it said. The different red shapes at the bottom right of both frames appear to confirm this.

The Kremlin’s official response to the UK’s accusations is markedly different from 2006, when two FSB assassins – Dmitry Kovtun and Andrei Lugovoi – poisoned the dissident and former FSB officer Alexander Litvinenko with a radioactive cup of tea.

Russia claimed the pair were themselves victims. Both gave numerous interviews, and appeared on pro-government channels. Lugovoi even became a celebrity politician in the state Duma and in 2015 received a patriotic honour from Putin.

In the Skripal case, however, Moscow has flat-out denied knowledge of Borishov and Petrov, even though they flew to London using genuine Russian passports – albeit with made-up names. Their fate and whereabouts are unknown.

Meanwhile, footage from a shop CCTV emerged showing how relaxed the suspects appeared to be as they walked back towards Salisbury railway station.

The pair halted outside Dauwalders, a dealer in stamps and other collectables and looked at a plastic container of vintage coins. They appeared to be about to try to go into the shop before realising it was shut as it was a Sunday and walking on.

Shop owner Paul Dauwalder said: “They looked very relaxed, as if they didn't have a care in the world, not at all as if they had just tried to allegedly kill someone.”

The footage was taken just after 1pm on Fisherton Street in the centre of Salisbury. Something appeared to catch the eye of the man known as Petrov and he stopped his colleague, Boshirov.

Dauwalder said the coins were foreign and not worth very much. “There may even be some coins from Russia or the Soviet Union,” he said. “It's surreal to think they were outside this shop and had a look in the window. Salisbury is a staid kind of city. It's not used to this sort of thing. I hope this footage will help build up the dossier of what happened and bring the perpetrators to justice.”

Another milestone in the six-month investigation came on Thursday when the police handed over Sergei Skripal's house to Wiltshire council. Until now it has been treated as a live crime scene.

It is believed there will now be a lengthy process of decontamination and testing at the house on Christie Miller Road involving the Department for Environment, Food and Rural Affairs and military experts. The ultimate plan for the house is not known.

After the house was handed over, civilian workers began arriving and setting up barriers at the rear of the property.