(Reuters) -Russia's FSB security service said on Friday it had revoked the accreditation of six British diplomats in Moscow after accusing them of spying and sabotage work, signalling the Kremlin's anger at what it sees as London's vital role in helping Ukraine.
Britain described the accusations as "completely baseless", saying it was a tit-for-tat action after the UK expelled the Russian defence attache and removed diplomatic status from several Russian properties in May.
Russia announced the expulsions hours before British Prime Minister Keir Starmer met U.S. President Joe Biden at the White House, a crucial step towards winning the go-ahead for Kyiv to use long-range missiles against targets in Russia.
The United States is "committed to standing with you to help Ukraine as it defends against Russia's onslaught of aggression," Biden told Starmer.
Neither Biden nor Starmer addressed long-range missiles in brief comments in front of reporters. The White House earlier said no announcement of any new policy on Ukraine was planned.
"I think the next few weeks and months would be crucial, very, very important that we support Ukraine in this vital war of freedom," Starmer said.
President Vladimir Putin said on Thursday that the West would be directly fighting with Russia if it allowed Ukraine to strike Russian territory with Western-made long-range missiles, a move he said would alter the nature and scope of the conflict.
The Kremlin said on Friday that Putin had delivered what it described as a clear and unambiguous message to the West which it was sure had been heard.
Washington and London see Iran's delivery of ballistic missiles to Russia to use against Ukraine, announced by Washington this week, as a dramatic escalation and it had sped up talks on Ukraine's long-range missile use, three Western sources said. Russia and Iran have denied any such deliveries.
The FSB, the main successor agency to the Soviet KGB, said it had documents showing that a British foreign office department in London responsible for Eastern Europe and Central Asia was coordinating what it called "the escalation of the political and military situation" and was tasked with ensuring Russia's strategic defeat in its war against Ukraine.
"The facts revealed give grounds to consider the activities of British diplomats sent to Moscow by the directorate as threatening the security of the Russian Federation," the FSB said in a statement.
"On the basis of documents provided by the Federal Security Service of Russia and as a response to the numerous unfriendly steps taken by London, the Ministry of Foreign Affairs of Russia, in co-operation with the agencies concerned, has terminated the accreditation of six members of the political department of the British Embassy in Moscow in whose actions signs of spying and sabotage were found," it said.
Britain said Russian accusations against its diplomats were baseless.
"The Russian authorities revoked the diplomatic accreditation of six UK diplomats in Russia last month, following action taken by the UK government in response to Russian state directed activity across Europe and in the UK," a British Foreign Office spokesperson said in a statement.
"We are unapologetic about protecting our national interests."
LONG-RANGE MISSILES
Russia's move to expel British diplomats ratcheted up tensions between Moscow and London, hours before Starmer landed in Washington to advance talks on getting the green light from Biden for Kyiv to use Britain's Storm Shadow missiles, which have a range of more than 250 km (155 miles), inside Russia.
Sources say the meeting is another step in talks to allow Ukraine to use Western long-range missiles against targets in Russia, something Ukrainian President Volodymyr Zelenskiy has been demanding for months.
A Western source said a decision could be made at the United Nations General Assembly which starts on Sept. 24.
White House spokesperson John Kirby downplayed the possibility of a change in U.S. policy.
"There is no change to our view on the provision of long-range strike capabilities for Ukraine to use inside of Russia," White House national security spokesman John Kirby told reporters on Friday.
"I would not expect any major announcement in that regard," from discussions between Biden and Starmer Friday, Kirby said.
The New York Times, citing European officials, reported that the United States looks set to approve the use by Ukraine of long-range missiles against targets in Russia on the condition that the weapons were not those provided by the United States.
SURVEILLANCE FOOTAGE
The six UK diplomats were named on Russian state TV, which also showed photographs of them. Surveillance footage of them was also released to Russian media, including covert video surveillance of a British diplomat meeting someone.
"The English did not take our hints about the need to stop this practice (of carrying out intelligence activities inside Russia), so we decided to expel these six to begin with," an FSB employee whose identity was hidden told the Rossiya-24 state TV channel.
The FSB said Russia would ask other British diplomats to go home early if they were found to be engaged in similar activity.
The Izvestia newspaper cited the FSB as saying that the British diplomats had recruited Russian teenagers, organised what it called provocations, and held talks in the British ambassador's Moscow residency with opposition figures.
It accused British diplomats of working with Russian activists to try to create divisions within Russian society around different ethnic groups and migrants and said many of the people involved in coordinating Britain's work on Ukraine based in London and Kyiv were working for the MI6 foreign intelligence service. It did not give details.
Russian Foreign Ministry spokeswoman Maria Zakharova said the activities of the British embassy in Moscow had gone well beyond the Vienna diplomatic conventions.
"More importantly, it is not just a question of formality and non-compliance with declared activities, but of subversive actions aimed at damaging our people," Zakharova said on Telegram.
(Reporting by Reuters; additional reporting by William James and Elizabeth Piper in London; Additional reporting by Doina Chiacu and Nandita Bose in Washington; Editing by Leslie AdlerWriting by Andrew OsbornEditing by Philippa Fletcher, Don Durfee and Alistair Bell)