Britain is now "directly involved" in the Ukraine war after its Storm Shadow missiles were used to strike targets inside Russia, according to Moscow's ambassador.
Speaking to Sky News' Mark Austin, Russian ambassador to the UK Andrei Kelin also accused Ukraine of using mercenaries from different countries in the fighting.
It comes after Western allies green-lit Ukraine's use of long-distance missiles to strike deep into Russia this week following months of requests from Kyiv.
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British Storm Shadow missiles were fired into Russia by Ukraine just days after US President Joe Biden authorised the same policy shift.
'Britain is now directly involved in this war'
In light of the move, Mr Kelin, when asked if the move had dragged Britain into the war, said: "Absolutely, Britain and UK is now directly involved in this war, because this firing cannot happen without NATO staff, British staff as well."
Asked what the difference was between that and Russia using Chinese, Iranian and North Korean equipment, technology and manpower - and whether they were directly involved too - Mr Kelin instead pointed to foreign fighters on the Ukrainian side.
"On that subject, I can say easily that we have plenty of mercenaries from different countries that are fighting right now on the side of Ukraine," he said.
Mr Kelin continued: "We just have seen in the Kursk area of the Polish unit, which has a special uniform worn by Polish soldiers. So what's the matter?"
Until this week, the UK said that British tanks, anti-tank missiles and other military equipment could be used inside Russia, but had kept restrictions on long-range missiles - echoing America's policy.
It isn't clear how big an effect the move will have on the war going forward, with fighting continuing in the east of Ukraine and in Russia's Kursk region.
Russia attacks Ukraine with ballistic missile - reports
On Thursday, unconfirmed reports emerged that the Kremlin had fired an intercontinental ballistic missile (ICBM) into Ukraine.
Ukrainian President Volodymyr Zelenskyy said the attack had the "characteristics" of a ICBM.
He added: "Today, our crazy neighbour has once again shown what he really is and how he despises dignity, freedom, and human life in general.
"He is so afraid that he is already using new missiles."
An investigation is under way to confirm the type of missile, he added.
A spokesperson for the British Prime Minister Sir Keir Starmer said reports of the missile's use were "deeply concerning".
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'We are not commenting on missile strike'
During a live briefing, a spokesperson for the Russian foreign ministry received a call and was told not to comment on reports of the Moscow-fired missiles, according to a video of the press conference.
While answering questions at a weekly briefing, spokeswoman Maria Zakharova was phoned by a man who used the informal "Mash" instead of Maria.
He told her not to comment on ballistic missiles.
"Yes, hello," Ms Zakharova said, according to the recording of the briefing.
"Mash," said the man, who was not identified.
"Yes, I am at a briefing," Ms Zakharova said.
"About the ballistic missile strike on Yuzhmash (rocket company Pivdenmash) that the Western media are talking about, we are not commenting at all," the man said.
(c) Sky News 2024: Britain 'directly involved' in Ukraine war, Russian ambassador tells Sky News