TWENTY-three Russian diplomats are being expelled from Britain after Theresa May said it was now clear Vladimir Putin and his government were to blame for the attempted murder of former spy Sergei Skripal and his daughter Yulia in the "barbaric" chemical weapon attack in Salisbury.

The expulsion of “undeclared intelligence officers,” representing just under half of Russia’s total diplomatic corps in the UK, is the biggest of its kind for more than 30 years. The diplomats have a week to leave.

In a sombre Commons statement, the Prime Minister confirmed Moscow had failed to meet the midnight deadline to provide a credible response to the assertion that the Salisbury incident was either state-directed by the Kremlin or was due to Russia losing control of its chemical weapons arsenal.

She told MPs: "There is no alternative conclusion other than that the Russian state was culpable for the attempted murder of Mr Skripal and his daughter and for threatening the lives of other British citizens in Salisbury, including Detective Sergeant Nick Bailey.

"This represents an unlawful use of force by the Russian state against the United Kingdom," declared Mrs May.

She explained that the Government had notified the Organisation for the Prohibition of Chemical Weapons about Russia’s illegal use of a nerve agent – the first in Europe since the Second World War - and it was working with the police to enable the watchdog to independently verify its analysis.

Following an earlier meeting with military and intelligence chiefs and senior ministers at the National Security Council, it was agreed to take immediate action to dismantle Russia's spy network in the UK.

The mass expulsion would, the PM claimed, "fundamentally degrade Russian intelligence capability in the UK for years to come", adding: "And if they seek to rebuild it, we will prevent them from doing so."

She stressed that law-abiding Russians living in the UK would continue to be welcome but added: "We will not tolerate the threat to life of British people and others on British soil from the Russian Government. Nor will we tolerate such a flagrant breach of Russia's international obligations."

Later, asked what the public should make of the Government having allowed 23 Russian spies to operate in the country to date, Mrs May’s spokesman said: “We don’t have discussions about national security in public.”

Other measures announced were:

*the suspension of all planned high level bilateral contacts between the UK and Russia, including revoking the invitation to Foreign Minister Sergei Lavrov to pay a reciprocal visit to London;

*confirmation there will be no attendance by UK Government ministers or members of the Royal Family at this summer’s World Cup tournament in Russia;

*targeting the finances of those responsible for human rights violations, tabling a "Magnitsky law" amendment to legislation currently going through Westminster, strengthening powers to impose sanctions on individuals:

*freezing Russian State assets wherever there is evidence they could be used to threaten the life or property of UK nationals or residents;

*using powers, normally targeted at suspected terrorists, to halt those suspected of hostile state activity at the border and Home Secretary Amber Rudd will consider whether new counter-espionage powers are required and

*stepping up checks on private flights and freight traffic to detect and track those who could endanger national security.

Mrs May also signalled approval for MI5 to review the Russian President's influence over "universities, think-tanks, financial institutions and political parties" in the UK but she did not raise the issue of banning the Kremlin-based channel RT; No 10 later made clear this was a matter for the media regulator Ofcom.

Sir Vince Cable for the Liberal Democrats spoke about action against Putin allies operating in the UK, including Igov Shevalov, the First Deputy Prime Minister, who owned a £14m flat overlooking the Ministry of Defence.

The PM told MPs: "Led by the National Crime Agency, we will continue to bring all the capabilities of UK law enforcement to bear against serious criminals and corrupt elites. There is no place for these people - or their money - in our country."

Moscow’s initial response came via the Russian Embassy in London, which denounced the expulsions as "unacceptable, unjustified and shortsighted".

Alexander Yakovenko, the ambassador, who had been summoned to the Foreign Office ahead of Mrs May's statement, said the UK Government's actions were "absolutely unacceptable and...a provocation."

It is expected that the Kremlin will announce a tit-for-tat expulsion of British diplomats and, possibly, other measures.

In the Commons chamber, Jeremy Corbyn condemned the "appalling act of violence" in Salisbury, telling MPs: “Nerve agents are abominable if used in any war; it is utterly reckless to use them in a civilian environment.”

But he stopped short of echoing the PM’s robust line on directly blaming Russia and again called for the Government to continue "robust dialogue" with Moscow.

When the Labour leader insisted it was a "matter of huge regret" that budgets to the diplomatic service had been cut, he was barracked loudly from the Conservative benches.

Mrs May told Mr Corbyn that there was a consensus on the response to Russia; it just did not extend to him.

One of her predecessors as Tory leader, Iain Duncan Smith, also upbraided the Labour leader for his response to the attack by Russia, which he said could now be regarded as a “rogue state”.

Mr Corbyn faced cries from Tory MPs of "that's how you do it" after Ian Blackford, the SNP’s Westminster leader, insisted a "robust response to the use of terror on our streets" was needed and pledged his party would work "constructively" with the Government.

However, the DUP's Sammy Wilson, in welcoming the “decisive action” taken by the PM, claimed it sat in contrast with the “policy of appeasement that we have heard from the frontbench of the Labour Party".

Later, the Labour leader’s spokesman, asked if he agreed with the PM that Russia was culpable, pointed out Mrs May’s two possibilities of direct state involvement by the Kremlin or a loss of control over its chemical weapons.

“We accept those alternatives are the ones most overwhelmingly likely,” said the spokesman, pointing out how the Labour leader had condemned the attack unequivocally and had “no problem” with the expulsion of Russian spies.

“Whoever carried out the attack - and the PM said she believed Russia was culpable - is responsible for a completely heinous and reckless attack in a civilian area with banned weapons.”

Stressing how international protocols regarding chemical weapons should be followed, the Labour spokesman was again asked who Mr Corbyn felt was to blame for the Salisbury incident and replied: “Clearly, it’s important to follow the evidence and be guided by it…

“The Government has access to information and intelligence on this matter, which others don’t. However, there is also a history in relation to weapons of mass destruction and intelligence, which is problematic to put it mildly. The right approach is to seek the evidence and to follow international treaties…”

When Mrs May’s words – “there is no alternative conclusion that Russia is culpable” – were put to the spokesman, he replied: “She is making clear culpability has different forms and so responsibility for the loss of control of weapons-grade nerve agent is clearly culpability.”

Meanwhile, the PM welcomed support from allies including the US, Nato and the EU, and said Britain would be pushing for a "robust international response" at the UN Security Council on Wednesday evening.

"This was not just an act of attempted murder in Salisbury nor just an act against UK; it is an affront to the prohibition on the use of chemical weapons. And it is an affront to the rules-based system on which we and our international partners depend," insisted Mrs May.