The Foreign Office dimissed what it called “baseless accusations” after Russia expelled a British diplomat on suspicion of spying.

The FSB security agency announced on Tuesday that the official had been stripped of his accreditation and given two weeks to leave the country.

The staff member “intentionally provided false information when receiving permission to enter our country, thereby violating Russian legislation,” the FSB told state media.

“At the same time, the Russian FSB has identified signs of the said diplomat conducting intelligence and subversive work that threatens the security of the Russian Federation.”

A spokesperson for the Foreign, Commonwealth & Development Office said: “This is not the first time that Russia has made malicious and baseless accusations against our staff. We will respond in due course.”

The diplomat was said to have joined the British contingent in Moscow as a replacement for staff who were expelled on suspicion of espionage in August.

The UK and other European countries have expelled hundreds of Russian diplomats during the war in Ukraine for the same reason.

Russia’s foreign ministry has also summoned the British ambassador, Nigel Casey, to lodge a complaint over the incident. Russian state media appeared to show him arriving at ministry headquarters in Moscow.

The meeting lasted for about an hour, Russian media reported.

The foreign ministry also announced it would tighten procedures around vetting British embassy staff, and warned it would take further steps if the UK “escalated” the situation.

Analysts suggested the move could have been related to the UK decision to allow Ukraine to use British-made Storm Shadow missiles against targets in Russia, after the US authorised the use of its own missiles for strikes on Russian soil.

Russian military bloggers reported that a Storm Shadow attack. in Kursk last week killed 18 soldiers, including senior officers.

“Storm Shadow fallout. Expect more to come,” posted Nikolaus von Twickel, a Russia analyst at German think-tank Zentrum Liberale Moderne, on social media.