The UK prime minister said the Kremlin was preparing a “fake story” that there were chemical weapons being stored in Ukraine to provide grounds for using them themselves, as he labelled the plan as “cynical, barbaric”.
“The stuff which you are hearing about chemical weapons is straight out of the Russian playbook,” he told Sky News’ Beth Rigby Interviews on Thursday.
“They start saying that there are chemical weapons that are being stored by their opponents or by the Americans so that when they themselves deploy chemical weapons, as I fear they may, they have a fake story ready to go.”
Western officials have been briefing in recent days how they fear a repeat of happened during the war in Syria, which saw the use of chemical weapons.
In a reference to the Salisbury nerve agent attack, Johnson added: “You have seen it in Syria, you saw it even in the UK. I just note that is what they are already doing. It is a cynical, barbaric government I’m afraid.”
Johnson was referring to repeated Russian accusations that the US was operating biowarfare labs in Ukraine – a claim dismissed as “laughable” by Washington.
Such assertions in Russian media increased in the run-up to Moscow’s military move into Ukraine and were made as recently as Wednesday by foreign ministry spokesperson Maria Zakharova.
Pentagon spokesman John Kirby said on Wednesday: “The Russian accusations are absurd, they are laughable and you know, in the words of my Irish Catholic grandfather, a bunch of malarkey. There’s nothing to it. It’s classic Russian propaganda.”
The UK has already accused the Russian government of war crimes, with the bombing of a maternity hospital in Mariupol being the latest atrocity in the campaign.
Earlier, foreign secretary Liz Truss said the government was “very concerned” about the potential use of chemical weapons.
“We’ve seen Russia use these weapons before in fields of conflict, but that would be a grave mistake on the part of Russia, adding to the grave mistakes that have already been made by Putin,” she told CNN.
White House press secretary Jen Psaki said the world should be “on the lookout” for the Russian use of chemical and biological weaponry.
She said “Russia’s false claims” about alleged US biological weapons labs and chemical weapons development in Ukraine could be an “an obvious ploy” by the Kremlin to try to “justify its further premeditated, unprovoked and unjustified attack on Ukraine”.
The attack on the Mariupol maternity hospital left three dead, including a child, and has been widely condemned.
Defence minister James Heappey told BBC Radio 4’s Today programme that UK intelligence believes the strike came from artillery rather than the air, but Britain is “still looking at exactly (what happened)”.
The Army veteran said that, even if Russian troops did not deliberately target the medical complex, the attack still amounts to a war crime.
Heappey told BBC Breakfast: “We ask ourselves the question ‘how did this happen?’ Was it an indiscriminate use of artillery or missiles into a built-up area, or was a hospital explicitly targeted?
“Both are equally despicable, both, as the Ukrainians have pointed out, would amount to a war crime.”
During a call with Ukrainian president Volodymyr Zelenskyy on Wednesday evening, Downing Street said prime minister Boris Johnson pointed out that the Mariupol bombing “was yet further evidence” that Putin was “acting with careless disregard for international humanitarian law”.
The World Health Organisation said it has confirmed 18 attacks on medical facilities since the Russian invasion began two weeks ago.
But Russia’s foreign minister Sergei Lavrov dismissed concerns about civilian casualties as the “pathetic shrieks” of Moscow’s enemies and claimed the Mariupol hospital had been used as a base by fighters from a far-right group.
Efforts continued to allow civilians to escape towns and cities including Mariupol and the Kyiv suburbs.
Conditions in Mariupol are grim, with food and water running short and some of trapped citizens resorting to melting snow to drink.
Western officials have described the refugee situation in Ukraine as “unprecedented”, with concerns that the number of people fleeing could reach four million within days.
So far around 2.2 million people have left Ukraine.