Russia's foreign minister has rejected the UK's claims that Moscow was behind the attack on former spy Sergei Skripal and his daughter Yulia as "nonsense", saying his country had "no relation" with the attempted murder.
Sergei Lavrov this morning claimed the UK had blocked him from accessing materials relevant to the case, and said Russia was "ready to cooperate" if the UK "meets its obligations under the Chemical Weapons Convention" – namely that it supply a sample of the nerve agent.
However this afternoon, a Downing Street spokesman said: "The UK fully complies with all obligations under the Chemical Weapons Convention."
The UK's ambassador Laurie Bristow was this morning summoned by the foreign ministry over the "baseless accusations". It dubbed the UK government's claim as "provocative" and said it suspects the poisoning is "another unscrupulous attempt of the British authorities to discredit Russia."
Yesterday Prime Minister Theresa May said the attack, which has left the two Skripals in intensive care and hospitalised a police officer, was "highly likely" to have been carried out by the Russian state.
Russia has until midnight tonight to offer a "credible" explanation for the attack. May said that if none were forthcoming she would announce measures against the state in the Commons tomorrow.
"If there is no credible response from Russia, the government will conclude it amounts to unlawful use of force by the Russian state against the UK," she said.
Overnight she was backed by US secretary of state Rex Tillerson, who said he had "full confidence in the UK's investigation and its assessment", adding "we are outraged that Russia appears to have again engaged in such behaviour".
Tillerson said: "From Ukraine to Syria – and now the UK – Russia continues to be an irresponsible force of instability in the world, acting with open disregard for the sovereignty of other states and the life of their citizens."
He said those responsible – not just those who carried out the attack using nerve agent Novichok, but also those who ordered it – "must face appropriately serious consequences".
"We stand in solidarity with our allies in the United Kingdom and will continue to coordinate closely our responses," he added.
Speaking to reporters today, Donald Trump said: "It sounds to me like it would be Russia based on all of the evidence they have. I don’t know if they’ve come to a conclusion. But she's calling me today... Theresa May is going to be speaking to me today. It sounds to me like they believe it was Russia, and I would certainly take that finding as fact."
He added: "As soon as we get the facts straight, if we agree with them, we will condemn Russia or whoever it may be."
Yesterday there were calls for the UK government to call on its allies when considering its next steps.
May told MPs there had been and would continue to be engagement with the UK's allies.
Last night May spoke with French President Macron, and agreed "it would be important to continue to act in concert with allies to address it," according to a Downing Street spokesman.
“President Macron condemned the attack and offered his solidarity with the UK. They agreed that the French and British governments should coordinate closely as the investigation developed and following Russia’s response," the spokesman added.
Boris Johnson this morning said he been encouraged by responses from many allies, in particular Macron, German foreign minister Sigmar Gabriel and Tillerson, who "last night made it absolutely clear that he sees this as part of a pattern of disruptive behaviour, increasingly disruptive behaviour, malign behaviour by Russia, the reckless use of chemical weapons, the support for the reckless use of chemical weapons which stretches from Syria now to the streets of Salisbury".
Johnson added: "The use of this nerve agent would represent the first use of nerve agents on the continent of Europe since the Second World War," describing the attack as "brazen".