The Russian Foreign Ministry revealed the nation would ignore Theresa May’s midnight deadline to explain why a nerve agent it developed in the 1970s was being used on British soil, as fears of all-out war mount.
The response comes after the prime minister said it was “highly likely” the Kremlin was behind the poisoning of former spy Sergei Skripal and his daughter Yulia in Salisbury.
But in a strongly-worded statement, the foreign ministry threatened to fight back.
Moscow said: “Any threats to take ‘sanctions’ against Russia will not be left without a response.
“The British side should understand that.”
Britain gave President Vladimir Putin until midnight on Tuesday to explain how a nerve agent developed by the Soviet Union was used to strike down a former Russian double agent who passed secrets to British intelligence.
But Russia denies it had anything to do with the attack and warned it will ignore the ultimatum until London hands over samples of the nerve agent used and begins to comply with its obligations under the Chemical Weapon Convention, which foresees joint investigations of such incidents.
The angry response comes after the Russian Embassy in the UK stated that the policy of the UK Government towards Moscow “is a very dangerous game”.
In a statement, the Embassy said: “Current policy of the UK Government towards Russia is a very dangerous game played with the British public opinion, which not only sends the investigation upon an unhelpful political track but also bears the risk of more serious long-term consequences for our relations.”
The Embassy continued to lambast the UK for its “unfounded accusations” and labelled events as a “source of concern”.
It went on: “Literally the next day after the first reports on the poisoning of Mr Skripal and his daughter the Embassy officially requested the Foreign Office to provide information on their health situation and the investigation.