RUSSIA has launched a tit-for-tat offensive against the UK in reaction to Theresa May's response to the nerve agent attack on Sergei and Yulia Skripal.

The country's Ministry of Foreign Affairs announced it had ordered 23 diplomats to leave within a week, moments after Britain's ambassador to Russia Laurie Bristow left the ministry in Moscow.

Other measures included closing the British Council and shutting down the British consulate in St Petersburg, while the country indicated it could take further action should there be what it called more "unfriendly" moves.

Bristow, speaking to reporters after being summoned, said the UK would "always do what is necessary to defend ourselves, our allies and our values against an attack of this sort".

Speaking at the Conservative Spring Forum, May said: "Today our ambassador in Moscow was informed by the Russian Government of the action they are taking in response.

"In light of their previous behaviour we anticipated a response of this kind and we will consider our next steps in the coming days alongside our allies and partners.

"But Russia's response doesn't change the facts of the matter – the attempted assassination of two people on British soil for which there is no alternative conclusion other than that the Russian state was culpable. It is Russia that is in flagrant breach of international law and Chemical Weapons Convention.

"I repeat today that we have no disagreement with the Russian people. Many Russians have made this country their home and those who abide our laws and make a contribution to our society will always be welcome.

"But we will never tolerate a threat to the life of British citizens and others on British soil from the Russian government."

The Foreign Office said the Government had "anticipated" a similar response to Theresa May's action to expel 23 Russian diplomats from London.

The National Security Council will meet early next week to consider the "next steps".

However, former UK ambassador to Russia Sir Roderic Lyne warned against a tit-for-tat battle. He told BBC Radio 4's Today programme: "I don't think it would be sensible to get dragged down into a mud-wrestling battle with a gorilla.

"We shouldn't put ourselves on the same level as the aggressor. We shouldn't allow Russia to turn this into a bilateral battle and have the Kremlin play it into the narrative of a hostile west, a hostile Britain out to attack Russia."

Counter-terrorism police have also renewed their appeal for sightings of Skripal's burgundy BMW 320D saloon car, registration HD09 WAO, in Salisbury on the morning of March 4.

Metropolitan Police Assistant Commissioner Neil Basu said: "We are learning more about Sergei and Yulia's movements but we need to be clearer around their exact movements on the morning of the incident."

It comes after NHS England said Detective Sergeant Nick Bailey, the police officer exposed to the Novichok agent in Salisbury, is no longer in a critical condition.

But Skripal, 66, the Russian ex-spy who was the target of the attack, and his daughter Yulia, 33, remain critical but stable in hospital.

Yesterday, the Russian foreign ministry tweeted an RT interview with Alexander Shulgin, Russia's permanent representative to the Organisation for the Prohibition of Chemical Weapons (OPCW), in which he suggested British authorities were "afraid".

He said: "My guess is actually our British friends and partners are afraid – they are afraid that our experts may analyse these samples and they may see some dirty tricks there or something. Our British partners don't want that to happen.

"If they don't produce any evidence we will regard that as they have nothing to show and they will be held accountable for slander."

Shulgin added: "For sure they will not be able to tell where the substance came from – this will require dialogue between Russia and the UK."

Foreign Secretary Boris Johnson said on Friday it was "overwhelmingly likely" that Vladimir Putin directed the use of the nerve agent on Britain's streets.

Johnson's comments were rebuked by Putin's spokesman Dmitry Peskov, who said: "Any reference or mentioning of our president is nothing else but shocking and unpardonable diplomatic misconduct."