Russia has revoked the accreditation of six British diplomats it has accused of spying.
The country’s security service FSB said in a statement it had received documents indicating Britain’s involvement in inflicting “a strategic defeat” on Russia.
The UK Foreign Office said the accusations against the diplomats were “completely baseless”. The BBC understands the diplomats involved left Russia many weeks ago.
It comes as Prime Minister Sir Keir Starmer arrives in Washington for talks with US President Joe Biden about the war in Ukraine, including whether to give Kyiv permission to fire their missiles at targets inside Russia.
Russian President Vladimir Putin has suggested Moscow will regard this as a serious escalation of the war which equates to “direct participation” of Nato countries.
“If that is the case, we will take corresponding decisions based on the threats that will be created to us,” he said on state TV.
The UK Foreign Office said Russia’s announcement was a response to action the UK had taken against Russian state-directed activity.
“We are unapologetic about protecting our national interests,” a spokesperson said.
Former national security advisor Lord Peter Ricketts said the allegations levelled at the six diplomats were “trumped up”.
He told BBC Radio 4’s Today programme it was a retaliatory punishment for the UK’s continued military support of Ukraine ahead of the meeting in Washington.
He added that it was Putin’s way of trying to “intimidate western politicians”.
Diplomatic accreditation is given by the host nation to recognise a person’s diplomatic status, as set out by the UN.
Without it, a person does not have official diplomatic status.
Announcing the decision on Friday, the FSB said the diplomats had shown signs of conducting intelligence and were tasked with inflicting a “strategic defeat on our country”.
In a Telegram post, Russian foreign ministry spokeswoman Maria Zakharova said Moscow “fully share[s] the assessments” made by the FSB on the activities of the diplomats.
“The British embassy has gone far beyond the limits outlined by the Vienna Conventions [UN treaty on diplomatic relations],” she said
An FSB officer told Russian media “hints” to “stop this practice [of gathering intelligence]”, were not heeded.
The security service added that it would revoke accreditation from more British diplomats if they are found to be involved in similar activity.
Noele Crossley, an associate professor in international security, told the BBC it was a “worrying sign that bilateral relations are deteriorating further.”
The University College London professor said “the diplomatic crisis reflects wider geopolitical and strategic tensions”, and added there may be “hostile rhetoric” still to come from Russia.
Prof Mark Galeotti, an expert on modern Russia at the Rusi think tank, told the BBC the revocation was bad news for an embassy already “pared to the bone” in a country the UK needed to maintain diplomatic connections.
He said that while former Soviet Union leaders would occasionally expel diplomats, they “understood that it was important to have robust diplomatic connections”.
President Putin, he said, has gone further, which is “alarming”.
The diplomats involved were named and pictured on Russian state TV earlier on Friday.
Expulsions of diplomats have become increasingly common since Russia’s full-scale invasion of Ukraine in February 2022.
Earlier this year, British diplomat Capt Adrian Coghill was given a week to leave Russia, days after the Russian defence attaché was expelled from London for alleged espionage as an “undeclared military intelligence officer”.
On Wednesday, UK Foreign Secretary David Lammy said the UK would provide £600m ($780m) in aid to Ukraine to support the country’s “humanitarian, energy and stabilisation needs”.
Last week’s summit in Germany also saw the UK commit to sending hundreds more short-range missiles to Ukraine, with the US pledging a further $250m (£189.9m) in military aid.
Additional reporting by Jacqueline Howard.
