The FSB security service said the diplomat appeared to have carried out “intelligence and subversive work, threatening the security of the Russian Federation”, state news agencies reported.
The development came hours after Russia confirmed it had arrested a British man captured fighting for Ukraine, amid heightened tensions between Moscow and the West over the state of the conflict, which began nearly three years ago.
The FSB said the diplomat had “deliberately provided false data when obtaining permission to enter our country, thus violating Russian law”.
Footage broadcast by state media showed Britain’s ambassador arriving at the foreign ministry in central Moscow after being summoned for talks, minutes after the expulsion was announced.
London and Moscow have expelled several of each other’s diplomats on spying allegations in recent years.
The FSB said the man expelled on Tuesday was a replacement for one of six British officials that Russia had expelled earlier this year, also on spying accusations.
Relations between the two capitals have been repeatedly strained by alleged spy scandals.
The current wave began with the 2006 assassination of former Russian agent and Kremlin critic Alexander Litvinenko in a London poisoning attack.
Then in 2018, Britain and its allies expelled dozens of Russian embassy officials they accused of being spies over the attempted poisoning of former double agent, Sergei Skripal, who was living in exile in Britain.
Skripal survived the attempted Novichok attack but a British civilian died after touching a contaminated perfume bottle, triggering uproar in London.
– British fighter arrested –
Also on Tuesday, a court in Russia’s western Kursk region confirmed a British citizen accused of fighting for Ukraine had been captured and arrested.
James Scott Rhys Anderson, 22, was ordered remanded in custody on allegations he had “participated in armed hostilities on the territory of the Kursk region”.
It was the first official confirmation from Russia of Anderson’s arrest, following a video that was published on pro-Kremlin Telegram channels over the weekend.
The video showed a man, who appeared to have his hands tied, identify himself as James Anderson.
In the footage, which could not be verified, the man said he joined the Ukrainian army after being dismissed from the British army in 2023.
UK Foreign Secretary David Lammy said on Monday that London had been “updated about that development” and would “offer this UK national all the support we can”.
Without specifying exactly what Anderson had been charged with or how long he had been ordered to remain in custody, the Leninsky court in Kursk said he was suspected of “committing a set of particularly serious offences that post a danger to society”.
Russia considers foreigners travelling to fight in Ukraine as “mercenaries”, enabling prosecution under its criminal code rather than treating them as prisoners of war under the Geneva Convention.
In 2022, a court in Russian-occupied eastern Ukraine sentenced two British fighters to death for fighting for Ukraine, although they were later released in a prisoner and POW exchange.
AFP