Ukraine has fired British-supplied Storm Shadow missiles into Russia, a source has told Sky News.

The UK and Ukraine have not yet confirmed the use of the long-range weapons in Russia but their deployment has been widely reported in British media.

Footage has been posted on Telegram reportedly showing wreckage from one of the missiles in Russia’s Kursk region, which borders Ukraine.

Ukraine war: Follow latest updates

The UK had previously said that British tanks, anti-tank missiles and other military equipment could be used inside Russia as part of Ukraine’s defence – but had kept restrictions on the use of long-range missiles.

It comes just days after US President Joe Biden authorised the same policy shift.

Russia’s defence ministry said on Tuesday that Ukraine had fired six US-supplied Army Tactical Missile Systems (ATACMS) in the Bryansk region.

A Russian state news agency cited the ministry as saying the missiles caused no casualties.

Missiles will have a ‘marginal effect’

Sky News’ security and defence editor Deborah Haynes says Ukraine’s allies have been pursuing a strategy of ambiguity and “it remains to be seen whether we get official confirmation on this from the UK or from Ukraine”.

“There is also the uncomfortable reality that Ukraine’s stockpile of Storm Shadow missiles is severely limited, so their use will only have a marginal effect.”

Embassies shut over air attack fears

Meanwhile, Sky’s military analyst Sean Bell says he would be amazed if this attack really marks the first time such a missile has been used by Ukraine to hit inside Russia.

“I would be quite surprised if they haven’t been used for selected targets further on [into Russia] because they are… very, very effective at striking Russian logistics hubs, headquarters, ammunition dumps,” he said.

Earlier, the US and some other Western embassies in Kyiv closed amid fears Russia was preparing a major air attack on the Ukrainian capital.

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Ukraine’s President Volodymyr Zelenskyy had been asking Kyiv’s allies to give his troops the capability to strike deeper behind Russian lines for over a year.

Mr Biden’s change of policy is linked to changing tactics by the Russians, which began deploying North Korean ground troops to supplement its own forces.

The White House is set to announce more military aid for Ukraine worth up to $275m (£217m), the US defence secretary has said.

Lloyd Austin said the support would “meet critical battlefield needs” and would include munitions for rocket systems, artillery and tank weapons, along with anti-personnel landmines.

Russian politician Maria Butina and the son of Donald Trump, the US president-elect, both warned the move could spark the start of a third world war.

Vladimir Putin lowered the threshold required for the use of nuclear weapons after America’s decision on long-range missiles for Ukraine, adding to fears the conflict could escalate.