Russia’s ambassador has been summoned to the UK Foreign Office over the expulsion of six British diplomats from Moscow, the government has said.

A Foreign Office spokesperson accused Russia of making “malicious and completely baseless accusations” against its staff, after Moscow claimed the diplomats were engaged in spying.

A statement accused Russia of carrying out a “malicious and deliberate public campaign of aggression against the UK”.

Russia revoked the accreditation of the diplomats on 13 September, with the country’s secret service, the FSB, saying it had received documents indicating Britain’s involvement in inflicting “a strategic defeat” on Russia.

In a statement, the Foreign Office spokesperson said the Kremlin was acting against an international treaty governing diplomatic relations.

Russia was carrying out a “deliberate campaign” aimed at undermining and threatening the UK’s security, as well as deterring its support for Ukraine, the spokesperson added.

The Foreign Office said this campaign was being carried out through “disinformation, acts of sabotage in Europe and direct harassment and restrictions against our diplomatic missions in Russia”.

“This campaign will not succeed. Russia must stop this activity immediately,” the statement added.

A news crew stationed outside the Foreign Office building in London were told by police on Wednesday afternoon the ambassador, Andrei Kelin, had been and left a few hours earlier.

Diplomatic accreditation is given by the host nation to recognise a person’s diplomatic status, as set out by the UN.

Without it, a person does not have official diplomatic status.

While the BBC understands the diplomats involved left Russia many weeks before being officially expelled, Moscow’s announcement coincided with Prime Minister Sir Keir Starmer’s visit to Washington, where he met US President Joe Biden.

They were due to discuss whether to allow Ukraine to fire Western long-range missiles at targets inside Russia.

Russian President Vladimir Putin suggested ahead of this trip that Moscow would regard this as a serious escalation in the war, which equates to the “direct participation” of Nato countries.

The diplomats involved, who were were named and pictured on Russian state TV, were the latest in a serious of similar expulsions – which have become increasingly common since Russia’s full-scale invasion of Ukraine in February 2022.

Earlier this year, British diplomat Capt Adrian Coghill was given a week to leave Russia, days after the Russian defence attaché was expelled from London for alleged espionage as an “undeclared military intelligence officer”.