The UK has called for an urgent meeting of the UN security council to update council members on the investigation into the nerve agent attack in Salisbury, the Foreign Office said, as Theresa May prepared to set out a range of reprisals against the Russian state.

The measures, which are likely to include the expulsion of diplomats, will be put to parliament in a statement by the prime minister on Wednesday, after a midnight deadline passed for the Kremlin to explain why a former spy was poisoned by a Russian-manufactured nerve agent.

Russia, which is a permanent member of the UN security council, said there would be retaliation against any fresh measures and that the UK had so far offered only “baseless accusations which are not backed up by any evidence”.

A spokesman for Vladimir Putin said Russia “rejects the language of ultimatums”, while a foreign ministry spokeswoman said Britain must not try to threaten Moscow, pointing to Putin’s recent speech in which he presented a range of new nuclear weapons.

The prime minister will lay out her proposals for reprisals in the House of Commons on Wednesday, after a day of diplomacy during which she sought support from the US president, Donald Trump, as well as Nato and EU allies including Germany’s chancellor, Angela Merkel.

May chaired the council, which is attended by a select group of cabinet ministers, including the Cabinet Office minister, David Lidington, the chancellor, Philip Hammond, the foreign secretary, Boris Johnson, the home secretary, Amber Rudd, and the defence secretary, Gavin Williamson, as well as May’s most senior security adviser, Mark Sedwill.

Downing Street said Trump had given his full backing to the UK in confronting Russia over the poisoning of the former double agent Sergei Skripal, after a chaotic 12 hours during which the president fired his secretary of state, Rex Tillerson.

The White House said the two leaders “agreed on the need for consequences for those who use these heinous weapons in flagrant violation of international norms”.

During the day, Johnson spoke to his French counterpart, Jean-Yves Le Drian, who said France was also prepared to take concrete measures. “The French government stressed particular concerns about Russia’s use of chemical weapons elsewhere, as is evident with their support to Assad’s murderous regime in Syria,” the Foreign Office said.

Both May and Johnson spoke to their German opposites, and the FCO said Berlin supported taking further steps against Russian disinformation.

Frans Timmermans, a vice-president of the European commission, said Europe should show a united front.

“It is of the utmost importance that those who are responsible for what has happened see very clearly that there is European solidarity – unequivocal, unwavering and very strong – so that those responsible are really punished for what they did,” he told the European parliament.

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In Moscow, Russian officials and prominent members of the foreign policy establishment on Wednesday reiterated threats that Moscow would respond harshly if punished for the Salisbury nerve agent attack.

The Russian foreign ministry summoned the British ambassador, Laurie Bristow, and warned that “actions by the British authorities are openly provocative”.

The Russian foreign minister, Sergei Lavrov, accused the UK of staging a “political performance” intended to mislead the international community and said accusations that Russia was likely to blame for poisoning Skripal were neither robust nor serious.

Among the options being considered by the UK are fresh sanctions, visa bans as well as the possibility of action by Ofcom against the Russian broadcaster RT. The watchdog said it had written to RT warning that an “unlawful use of force” by Russia against Britain would trigger a fast-track investigation to potentially revoke its licence.



“Not a single British media outlet will work in our country if they close Russia Today,” the foreign ministry spokeswoman said.

Sanctions would provoke “contempt and a harsh response”, Sergey Karaganov, an influential foreign policy analyst who heads Russia’s Council on Foreign and Defence Policy, told the Guardian by telephone on Wednesday morning. “We don’t care what Britain threatens us with. The proposed punishments look ridiculous.”

Russian officials continued to protest the country’s innocence. Members of parliament tasked with the portfolio for chemical disarmament said Russia no longer had any stores of chemical weapons.

The novichok nerve agent, “just like any other stockpiled over the previous period, has been scrapped”, the MP Vladimir Gutenev told reporters on Wednesday.

Labour is set to argue that the government should formally support amendments to the sanctions and anti-money-laundering bill to target human rights abusers, named the “Magnitsky clause” after the Russian accountant who died after revealing state-sponsored fraud.

The shadow chancellor, John McDonnell, said the measures would “hit them in the pocket” and could be applied to human rights abusers anywhere in the world.

The Labour leader, Jeremy Corbyn, will respond to May’s statement on Wednesday afternoon, having been criticised by some of his own backbenchers for his initial response, which attacked the Conservatives for accepting donations from Russians.



McDonnell said the response had not been ill-judged and Corbyn wanted due process to be followed. “He was very careful to say we have to have due process on this, both to give the government time, and yes even Russia time to respond,” he told BBC Radio 4’s Today programme.

“I think he got the tone exactly right, to make sure no one could criticise us for not having due process.”

On Tuesday evening, the Metropolitan police launched a counter-terrorism investigation into the death of another Russian exile in London, Nikolai Glushkov, a close friend of the oligarch and Putin opponent Boris Berezovsky. The Met said it was “a precaution because of associations that the man is believed to have had”.