Britain lashed back at Russia today and has threatened to close down the Russian trade mission in north London.

The UK described the mission in Highgate as 'den of spies' and a source confirmed closing the mission was 'something we will look at' as the Kremlin stepped up the war of words by declaring more British diplomats should be expelled.

Last night, Russia accused Britain of 'provocation' after a 'rummage' team of UK border officials searched an Aeroflot flight from Moscow - something which the Metropolitan Police deny took place.

Putin's government has four bases in the UK, including its embassy, a consulate, the trade mission and a country estate in the Home Counties.

One source confirmed the government was looking into shutting down the trade mission, adding 'The Highgate one is a den of spies', according to the Telegraph.

Britain also unveiled retaliations against EU countries - who along with the US and other allies have launched a bruising wave of sanctions in solidarity with the UK.

But the Foreign Office dismissed the latest swipe, saying the sabre-rattling by Moscow did not 'change the facts'.

British ambassador Laurie Bristow told reporters in the Russian capital: 'It is important to remember why this crisis has arisen.

'It is the use of a chemical weapon on the streets of the UK.'

The latest round of tit-for-tat was signalled earlier when Mr Bristow and his counterparts from states including France, Germany, Holland, Australia and Canada were summoned by the foreign ministry.

Britain lashed back at Russia today and has threatened to close down the Russian trade mission (pictured) in north London

Russia's President Vladimir Putin (L) and Russia's Energy Minister Alexander Novak during a meeting at the Moscow Kremlin

The Kremlin stepped up the raging row by declaring that more UK diplomats are being expelled

The latest round of titi-for-tat was signalled earlier when British ambassador Laurie Bristow (pictured) and his counterparts from France, Germany, Holland and Canada were summoned

Russia's President Vladimir Putin (centre), and Prime Minister Dmitry Medvedev (third left) at a meeting of the Security Council of Russia in the Kremlin

A man carries boxes out from the U.S. consulate as a Russian police officer guards the entrance, in St. Petersburg, Russia, Friday

Sergei Skripal (left) remains in a critical condition after the attack in Salisbury on March 4. and The condition of his daughter Yulia (right) is said to have improved

Moscow's foreign ministry gave Britain a month to cut its diplomatic staff to the same numbers as Russia has in Britain.

Russia has already vowed to expel 60 US diplomats and close Washington's consulate in Saint Petersburg, mirroring the action by America.

In all, more than 150 Russian diplomats have been ordered out by 29 nations including the US, EU members, and Nato countries. The UK expelled 23.

Ambassadors from 23 nations - Albania, Australia, Canada, Croatia, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Ireland, Italy, Latvia, Lithuania, Macedonia, Moldova, the Netherlands, Norway, Poland, Romania, Spain, Sweden and Ukraine - were today told to send home the same number of staff they had ejected.

Russian also said it 'reserves the right to take retaliatory measures' against Belgium, Hungary, Georgia and Montenegro.

A Foreign Office spokeswoman said: 'It's regrettable but in light of Russia's previous behaviour, we anticipated a response.

'However, this 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.

'Russia is in flagrant breach of international law and the Chemical Weapons Convention and actions by countries around the world have demonstrated the depth of international concern.'

Dutch ambassador Renee Jones-Bos said she had been told two diplomats would be expelled.

'Two of my colleagues are leaving Moscow. But we (the embassy) are staying here,' state news agency TASS quoted her as saying.

Security personnel carry pieces of furniture out of the US consulate in St Petersburg, Russia

Time to go: British Ambassador to Russia Laurie Bristow leaves the Russian foreign ministry building in Moscow, Russia

Should I stay or should I go: Ambassador of the Netherlands to Russia Regina Veronica Maria Jones-Bos and German ambassador to Russia Ruediger Von Fritsch arrives at the Russian Foreign Ministry headquarters

French Ambassador Sylvie Bermann was also brought in to be informed of reprisals

A swathe of European states have expelled Russian diplomats alongside Canada and the US

Former double agent Sergei Skripal is still in critical condition following the Novichok nerve agent attack in Salisbury on March 4 - although his daughter Yulia has suprised doctors by showing signs her condition is improving.

The UK and its allies insist that only a state actor could produce and deploy the nerve agent - while Mr Putin has previously called for 'traitors' to get their comeuppance.

Russia's foreign minister Sergei Lavrov has suggested that its diplomatic response could be greater than the sanctions it has suffered.

Vladimir Putin's spokesman today blamed the West for triggering the diplomatic meltdown.

'Russia did not unleash any diplomatic war,' Dmitry Peskov said.

'Russia never initiated any exchange of sanctions.'

He said Russia had been 'forced to take retaliatory steps in response to hostile, illegal actions' by Washington.

But US state department spokeswoman Heather Nauert said: 'It's clear from the list provided to us that the Russian Federation is not interested in a dialogue on issues that matter to our two countries.'

White House Press Secretary Sarah Sanders said Russia's expulsion of US diplomats marked a 'further deterioration' in relations between the two countries.

Vladimir Putin, pictured in the Kremlin this week, has denied Russia was involved in the attack