Vladimir Yermakov, the Russian foreign ministry head of non-proliferation, held a “briefing” for foreign diplomats in Moscow during which he questioned whether the incident, which left former Russian double agent Sergei Skripal, 66, and his daughter, Yulia, 33, fighting for their lives even involved a nerve agent.
But his briefing was interrupted when British diplomat Emma Nottingham said there had been “a barrage of distortion and misinformation” as well as “an unlawful use of force against the United Kingdom.”
Mr Yermakov fired back: “Get yourself out of your Russophobia and your island mentality. I feel ashamed for you.”
The Russian Foreign Ministry event in Moscow was attended by dozens of foreign diplomats and broadcast on state TV.
But the two sides launched sharp allegations against each other over the nerve agent attack.
The attack in Salisbury, England, has plunged ties between London and Moscow into their worst crisis since the Cold War.
Britain has blamed Russia for the attack – something Moscow denies – and both have expelled diplomats in the standoff.
Russia had organised Wednesday’s event to explain its stance and lost little time in alleging that Britain itself had either directly or indirectly orchestrated the attack or had allowed “a terrorist attack” to take place on British soil.
Mr Yermakov added: “Nobody understands what happened in Salisbury. Let’s investigate what really happened.”
However, Ms Nottingham said it was “highly likely” that Moscow stood behind the attempted assassination of the Skripals for four reasons: “The identification of the chemical agent by our world leading scientists, our knowledge that Russia has previously produced this agent … Russia’s record in conducting state-sponsored assassinations … and our assessment that Russia views defectors as legitimate targets.”
Many ambassadors including those of Britain, France, Germany and the United States, stayed away from the Moscow event, sending more junior officials instead.
Key Western countries criticised Russia and offered Britain their support.
US President Donald Trump and French President Emmanuel Macron reiterated solidarity with Britain in a telephone call on Wednesday and “agreed on the need to take action to hold Russia accountable”, the White House said.