A “sordid” alliance between Russia and Iran is threatening global security, James Cleverly warned as the UK imposed sanctions on “high level” figures from both countries.
Weapons supplied by Tehran have been used by the Russian military in the Ukraine war.
Vladimir Putin’s forces have used Iranian drones to carry out strikes on Ukrainian towns and cities and key energy infrastructure.
Foreign Secretary Mr Cleverly said: “Iran and Russia’s sordid deals threaten global security. We are holding their desperate alliance to account.
“The UK has just sanctioned high-level Russian and Iranian figures in response to the abhorrent strikes against civilian targets.”
The Foreign Office said evidence from the US indicates Iran is becoming one of Russia’s top military backers.
Russia intends to provide Iran with advanced military components, increasing the risk to Middle East and international security, officials said.
Twelve senior commanders of Russian military forces, including units implicated in attacks on Ukrainian cities, were hit with asset freezes and travel bans under the new UK sanctions.
Major General Robert Baranov, identified by investigative website Bellingcat as the commander of a unit responsible for programming and targeting Russian cruise missiles, is among those affected.
The sanctions also include individuals linked to the Iranian drones used by Mr Putin’s forces in Ukraine, including the co-owner and managing director of Mado, the company responsible for manufacturing engines for the unmanned aerial vehicles.
Mr Cleverly said: “The UK stands with Ukraine. Russian forces’ calculated attacks on cities and innocent civilians in Ukraine will not go unanswered.”
He said the Tehran government was “increasingly isolated in the face of deafening calls for change from its own people” and was making deals with Russia as “a desperate attempt to survive”.
Meanwhile, UK defence intelligence suggests Mr Putin has cancelled his regular end-of-year press conference because of concerns that the “special military operation” in Ukraine would be raised.
The Ministry of Defence said: “This will be the first time in 10 years that Putin has not held the annual event, while the usual public phone-in also did not take place this year.”
The MoD said Kremlin officials “are almost certainly extremely sensitive about the possibility that any event attended by Putin could be hijacked by unsanctioned discussion about the ‘special military operation’”.