Britain will expel Russia's defence attache, remove diplomatic status from some properties and limit the length of Russian diplomatic visas in response to what interior minister James Cleverly called Moscow's "malign activity".
Britain's action was among several taken across Europe on Wednesday. Estonia summoned the head of the Russian embassy to protest the jamming of GPS signals and Poland said it had been targeted by a hacking attack from a Russia-linked group.
Addressing parliament on Wednesday, Cleverly said Britain was already "an extremely challenging operating environment for Russian intelligence services" but the measures would "only serve to strengthen our resilience to the Russian threat".
Britain has introduced several waves of sanctions on Russian companies and individuals since Moscow launched its full-scale invasion of Ukraine, and Cleverly said the Conservative government would not falter in its support of Kyiv.
"We will expel the Russian defence attache, who is an undeclared military intelligence officer," Cleverly said.
"We will remove diplomatic premises status from several Russian-linked properties in the UK ... We are imposing new restrictions on Russian diplomatic visas, including capping the length of time Russian diplomats can spend in the UK."
Russian foreign ministry spokeswoman Maria Zakharova said Russia would give an "appropriate response" to Britain's move.
In April, a British man was charged over alleged hostile state activity intended to benefit Russia, including by allegedly recruiting others for an arson attack on a Ukrainian-linked commercial property in London.
Cleverly said he expected Britain's latest measures would prompt "accusations of Russophobia, conspiracy theories and hysteria from the Russian government", but the British government would "not be taken for fools".
"Our response will be resolute and firm," he said. "Our message to Russia is clear, stop this illegal war, withdraw your troops from Ukraine, cease this malign activity."
