Russia has expelled a British diplomat accused of espionage, summoning London's ambassador to the foreign ministry in Moscow.

The FSB security service claims the diplomat engaged in intelligence and subversive activities, which threatened Russian security.

This incident follows the arrest of a British man, James Scott Rhys Anderson, 22, accused of fighting for Ukraine in Russia's Kursk region.

Anderson, who reportedly joined the Ukrainian army after leaving the British army in 2023, was shown in a video with his hands tied, claiming participation in armed hostilities.

The escalation in tensions is part of an ongoing series of spy scandals between the two nations, marked by past high-profile cases like the 2018 poisoning of Sergei Skripal.

Both countries have a history of expelling each other's diplomats amidst such allegations.

UK Foreign Secretary David Lammy stated that the UK would support Anderson, who is held on charges perceived as a threat to society.

Under Russian law, foreign fighters in Ukraine are treated as mercenaries, complicating their legal status under the Geneva Convention.