MOSCOW has contemptuously dismissed Theresa May’s ultimatum over the Salisbury chemical attack as a “circus show in the British parliament".

Maria Zakharova, the Russian Foreign Ministry spokeswoman, said: "The conclusion is obvious; it's another information and political campaign based on provocation."

She then added: "Before making up new fairy tales, let the British disclose how the Litvinenko case ended."

READ MORE: Theresa May's ultimatum to Vladimir Putin: respond credibly or face "full range" of UK measures

In 2006, the Russian dissident Alexander Litvinenko was poisoned with radioactive polonium-210 in London in 2006.

One of his suspected killers, Andrei Lugovoi, now a Russian MP, dismissed the Prime Minister’s decision to point the finger at Moscow so quickly as “at a minimum irresponsible”.

Earlier as it became clear Mrs May was preparing to accuse the Putin Government, a Russian embassy spokesman accused the UK Government of playing a "very dangerous game" with British public opinion and warned of the risk of "serious long-term consequences".

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In a statement on its website, the embassy said: "We would like to stress once again that we are outraged by the anti-Russian media campaign, condoned by the Government, that influences the investigation and has a psychological effect on British residents.

"Our compatriots and British nationals of Russian origin are worried about their future in this country. UK-based Russian journalists are receiving threats.

"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."

Meanwhile, Vladimir Putin dismissed questions about his state's alleged involvement in the Skripal case.

On a visit to a grain centre, the Russian President told the BBC: "We're dealing with agriculture here...and you talk to me about some tragedies. Get to the bottom of things there, then we'll discuss this."

READ MORE: Nerve agent in Salisbury attack ‘clearly came from Russia’, says Rex Tillerson

In the Commons, Mrs May explained: “Based on the positive identification of this chemical agent by world-leading experts at the Defence Science and Technology Laboratory at Porton Down; our knowledge that Russia has previously produced this agent and would still be capable of doing so; Russia's record of conducting state-sponsored assassinations; and our assessment that Russia views some defectors as legitimate targets for assassinations; the Government has concluded that it is highly likely that Russia was responsible for the act against Sergei and Yulia Skripal."

As MPs urged the PM to seek the support of allies and No 10 suggested she would make a raft of international phonecalls to her foreign counterparts, possibly including Donald Trump.

In Washington, Sarah Huckabee Sanders, the White House Press Secretary, said: "We've been monitoring the incident closely, taking it very seriously. The use of a highly lethal nerve agent against UK citizens on UK soil is an outrage.

"The attack was reckless, indiscriminate and irresponsible. We offer the fullest condemnation and we extend our sympathy to the victims and their families and our support to the UK Government.”

She added: "We stand by our closest ally and the special relationship that we have."

Meanwhile, MPs called for the Kremlin-backed television channel RT, formerly Russia Today, to be banned from broadcasting in the UK.

Labour’s Chris Bryant said: "Can we just stop Russia Today just broadcasting its propaganda in this country?"

His Welsh colleague Stephen Doughty added: "On Russia Today, can I urge the Prime Minister to speak with the Secretary of State for Culture, Media and Sport to look at reviewing Russia Today's broadcasting licence, and to speak to the House authorities about blocking their broadcasts in this building itself. Why should we be watching their propaganda in this Parliament?"

READ MORE: Theresa May's ultimatum to Vladimir Putin: respond credibly or face "full range" of UK measures

Mrs May appeared to not rule out taking such action should she deem it necessary as she pointed out that, if Moscow responded unsatisfactorily, then the UK Government would look at a “range of measures which could be necessary”.

Alex Salmond, the former First Minister, has come in for criticism for fronting a talk show on the channel, which many parliamentarians regard as nothing more than a propaganda mouth-piece for the Putin Government.