UK Foreign Office calls allegations ‘completely baseless’ as tensions escalate over war in Ukraine.

Russia has revoked the accreditation of six British diplomats in Moscow accusing them of espionage and sabotage.

In its announcement on Friday, Russia’s Federal Security Service (FSB) said the diplomats carried out “subversive activities and intelligence” gathering, adding that it has “documentary” proof confirming the United Kingdom’s “coordination of an escalation in the international political and military situation” in Ukraine.

The British government called the Russian accusations “completely baseless”.

The Foreign Commonwealth and Development Office said on Friday that this was a tit-for-tat measure after Western moves against “Russian state-directed activity across Europe and in the UK”.

The six diplomats have already left Russia and been replaced.

“We are unapologetic about protecting our national interests,” said the foreign office statement.

The Russian announcement came hours before a planned meeting in Washington, DC, between British Prime Minister Keir Starmer and US President Joe Biden as they are expected to discuss the Ukraine war.

The FSB, the successor of the Soviet-era agency KGB, said the British foreign ministry’s Eastern Europe and Central Asia department was coordinating moves aimed at inflicting a “strategic defeat” on Russia.

Reporting from Moscow, Al Jazeera’s Yulia Shapovalova said the latest expulsion was “not surprising”, adding that diplomatic relations between the two countries are at “a historic low”.

In May, the UK announced it was expelling the Russian defence attache for spying, and removed diplomatic premises status from several Russian properties.

It also imposed a five-year limit on Russian diplomats’ postings, which led to many of them leaving the country.

The Izvestia newspaper cited the FSB as saying the British diplomats had recruited Russian teenagers, organised what it called provocations, and held talks in the British ambassador’s Moscow residency with opposition figures.

The six diplomats were named on Russian state TV, which also showed photographs of them. Surveillance footage of them was released to Russian media, including covert video surveillance of one envoy meeting someone.

The spokeswoman of Russia’s Ministry of Foreign Affairs, Maria Zakharova, said her ministry agreed with the FSB’s “evaluation”, adding that “the British embassy has largely flouted the limits set by the Vienna Convention”.

Since taking office, Starmer has reaffirmed his country’s support for Ukraine as “unwavering”.

He is expected to discuss with Biden whether to let Ukraine use Western-supplied and made long-range weapons inside Russia.

But concerns are already being raised about the political and military repercussions of such a decision, said Al Jazeera’s Jonah Hull, reporting from London.

President Vladimir Putin warned on Thursday that if Western nations allow Ukraine to use long-range weapons to strike inside Russia then it will mean NATO would be “at war” with his country.