Foreign Minister Sergei Lavrov also said Russia does not intend to comply with British Prime Minister Theresa May's demand Monday for an official explanation of how a nerve agent identified as Novichok, which was developed by the former Soviet Union, allegedly came to be used in the poisoning attack in southern England.
Lavrov insisted that Russian experts should be able to examine the British evidence but again denied Russian involvement in last week's attack.
The Foreign Ministry later said Russia would retaliate for any sanctions imposed by London in response to the attack. "Any threats will not remain unanswered," the ministry said in a statement. "The British side should be aware of that."
The ministry said it presented the British ambassador with "a strong protest over the unfounded accusations leveled at Russia by British authorities" and stressed that "Moscow would not respond to London's ultimatum until the Russian side is provided with samples of the chemical substance."
British authorities say a deadly nerve agent was used to poison former Russian double agent Sergei Skripal and his daughter in the city of Salisbury, about 88 miles southwest of London. Both remain comatose.
May said use of the chemical, which is believed to be unique to Russia, made Moscow's complicity "highly likely."
According to the Interfax news agency, Lavrov denied that Russia had anything to do with Skripal's poisoning and reiterated Moscow's willingness to cooperate if information related to the nature of the chemical agent was shared with Russia.
Lavrov said Britain has an obligation to share forensic data under the Convention on the Prohibition of Chemical Weapons. Russia also summoned the British ambassador, Laurie Bristow, following the allegations, Interfax reported.
"Before delivering ultimatums to report to the British government within 24 hours," Lavrov said at a news conference in Moscow, "it is better to comply with your own obligations under international law - in this case the Convention on the Prohibition of Chemical Weapons."
Russia's representative to the Organization for the Prohibition of Chemical Weapons, Alexander Shulgin, told a meeting of the group's executive board Tuesday that London's allegations of Russian involvement were unfounded and unacceptable. Interfax reported. He called on Britain to turn over samples to the organization for independent laboratory analysis.
Earlier on Tuesday, Russia's Foreign Ministry and pro-Kremlin lawmakers derided Britain amid a deepening showdown.
May said Russia either engaged in a direct attack against Britain or lost control of the nerve agent it developed. Britain will not tolerate such a "brazen attempt to murder innocent civilians on our soil," she warned.
The British leader stopped short of announcing retaliatory actions, saying she would give Russia a chance to respond to her government's findings and would return to Parliament on Wednesday with a plan for specific action.
But in her remarks, May described a "reckless" and "indiscriminate" attack against the 66-year-old Skripal and his daughter Yulia, 33. A police officer also remains hospitalized.
On the Russian Foreign Ministry's verified Twitter account, the posts carried a characteristically flippant and sarcastic tone. It launched a hashtag, #HighlyLikelyRussia, and portrayed May's ultimatum as part of broader anti-Russian hysteria plaguing Western discourse.
The post included a video of recent intense snowfall in Britain, mockingly suggesting that Russia was to blame for the weather. The video concludes with an image of a penguin, and signs off with "at least penguin enjoys it."
Other Foreign Ministry accounts, such as one belonging to Russia's embassy in South Africa, struck similar notes.
Meanwhile, Konstantin Kosachev, the head of the Foreign Affairs Committee in the Federation Council, Russia's upper chamber of parliament, wrote on Facebook that May's accusations were "despicable and unacceptable."
"For Britain, the Queen of Courts, this is a complete degradation," Kosachev wrote. "The accused has to provide the proof, not the court or the prosecutor, without being given access either to the evidence or the trial itself."
Vyacheslav Volodin, speaker of the Russian State Duma, the lower house of parliament, asserted that the British allegations were part of a planned effort to meddle in Sunday's Russian presidential election.
"It is during this period that these events unfold in order to try to discredit Russia in the eyes (of) the international community, in order to create this unfavorable background in the conduct of the election campaign," he said, according to Interfax. Citing "this interference in our elections," he added: "The form chosen is the most cynical, when the health of citizens is put at risk. . . . Once again I want to say that Britain is responsible for this."
His counterpart in the Federation Council, Valentina Matvienko, echoed his words.
"In Russia, a very important political campaign is underway on preparing for the presidential election," Matvienko said. "This is another fake aimed at whipping up another round of the Russophobic campaign."
While most of the reactions have so far avoided the topic of Novichok, the nerve agent identified by May in the poisoning of the Skripals, other members of Russia's Federation Council addressed the accusations head-on.
Council member Igor Morozov, a veteran of the Russian security services, told the RIA Novosti news agency that "Russia has not only stopped producing nerve agents, including Novichok, but also completely destroyed all of its stockpiles."
However, he also said it would be "dangerous but possible" to secretly produce Novichok, although that would require special facilities and technicians.
Last year, the Organization for the Prohibition of Chemical Weapons announced the destruction of Russia's final batch of declared chemical weapons. However, Russian scientists who blew the whistle on Novichok's existence in 1992 claimed at the time that the nerve agent was designed specifically to skirt chemical weapons conventions.
Secretary of State Rex Tillerson, speaking to reporters en route back to Washington from a trip to Africa, said the nerve agent "clearly came from Russia," and he warned of consequences. Hours after Tillerson backed the British accusation, the White House announced Tuesday that he would be replaced as secretary of state by CIA Director Mike Pompeo.
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