Russia has expelled 23 British diplomats in a tit-for-tat response that further escalates global tensions over the Salisbury poisoning incident.

It also threatened possible “further retaliatory measures” after Theresa May kicked out 23 Russian diplomats who she claimed were undeclared intelligence officers.

Relations between Westminster and Moscow soured after the poisoning of former Russian double agent Sergei Skripal, 66, and his daughter Yulia, 33.

Moscow summoned Britain’s ambassador Laurie Bristow on Saturday to tell him of the expulsions.

Moscow is also closing the British Council, which promotes British culture internationally, in Russia.

It also said it would withdraw permission for a British consulate to open in St Petersburg.

Speaking to journalists as he left, Bristow said the UK would “always do what is necessary to defend ourselves, our allies and our values against an attack of this sort”.

The Russian Ministry of Foreign Affairs blamed Britain’s “provocative actions” in making “groundless accusations against the Russian Federation with regard to the incident in Salisbury”.

It added: “The British side is warned that in case of further unfriendly actions against Russia, the Russian side reserves the right to take further retaliatory measures.”

The British Council said in a statement: “We are profoundly disappointed at this development.  It is our view that when political or diplomatic relations become difficult, cultural relations and educational opportunities are vital to maintain on-going dialogue between people and institutions.

“We remain committed to the development of long-term people-to-people links with Russia as we do in over 100 other countries.”

The diplomats have a week to leave.

The Foreign Office said it had “anticipated a response of this kind and the National Security Council will meet early next week to consider next steps”.

It said in a statement: “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 the Chemical Weapons Convention.

“We have no disagreement with the people of Russia and we continue to believe it is not in our national interest to break off all dialogue between our countries but the onus remains on the Russian state to account for their actions and to comply with their international obligations.” 

After the explusions, Theresa May told the Conservative Spring Forum: “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 tension has risen since the poisoning on March 4 and descended into mockery after Defence Secretary Gavin Williamson said Russia should “go away and shut up”.

Moscow’s foreign minister, Sergei Lavrov, dismissed the “bombastic remarks”, suggesting Williamson “lacks education”.

Lavrov added: “Theresa May’s ‘highly likely’ is the main argument supporting the Russia blame game and his would be ‘Russia should go away and shut up’.

“Maybe he lacks education, I don’t know.” 

Full UK response to Salisbury attack:

• 23 Russian diplomats expelled.
• Creating new power to detain those suspected of Hostile State Activity at the UK border. 
• Increase checks on private flights, customs and freight.
• Freeze Russian State assets wherever we have the evidence that they may be used to threaten the life or property of UK nationals or residents.
• Suspend all planned high level bi-lateral contacts between the UK and Russia, including revoking the invitation to Foreign Minister Sergey Lavrov to visit to the UK.
• No attendance by Ministers – or indeed Members of the Royal Family – at this Summer’s World Cup in Russia. 
• A new £48m chemical defence centre based at Porton Down to face the “increasing” threat from Russia and North Korea. 
• Special UK troops to receive anthrax vaccine. 

Russia’s ambassador in London, Alexander Yakovenko, said Williamson’s comments were part of a “shocking” political culture.

He told RT television: “I have some reservations about the political culture, in the way discussion is going on and the way the minister of defence is putting his views.

“It is quite surprising for us, but this is the new reality in the new political culture in the United Kingdom.

“For the Russian ear, and the ear of any diplomat in the world, it is a little bit shocking.

“But when you live here in London for a while, you can get used to this.”

Yakovenko added that the Government is using the Salisbury poisoning case to divert attention from Brexit.

“There is one more reason for diverting the attention of the British public, which is Brexit, because the situation in negotiations is not so easy … In order to divert attention from Brexit, they have to present something to the public that could move a little bit to the other side.

“That’s a great possibility to launch this anti-Russian campaign. This is a scenario that was written in London but it’s a short-sighted scenario because, in the long run, Britain will have to explain what is behind all these things in Salisbury.”

The Skripals were poisoned with a military grade agent that was made in Soviet-era Russia.

Donald Trump, Emmanuel Macron, Angela Merkel all signed a joint declaration calling the poisoning the “first offensive use” of a nerve agent in Europe since the Second World War.

They called it an “assault on UK sovereignty” and a “clear violation of the Chemical Weapons Convention and a breach of international law”.

Speaking at an election campaign event in Moscow on Thursday night, Russian president Vladimir Putin said Russia was a “proud” nation “and will be in the future, too”.