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.
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.”
Meanwhile, Sky’s military analystSean 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.
The same missiles are also used by French forces, using the alternative name SCALP, and are made by the Anglo-French arms manufacturer, MBDA.
What are storm shadow cruise missiles?
The air-to-air missile has a strike capability of nearly 200 miles (300km) – meaning it would potentially allow Ukraine to hit further into Russian territory.
The missile weighs 1.3 tonnes and is just over 5m long.
It is launched from the air, and in theory can be used from Ukraine’s Soviet-made jets.
UK-owned Storm Shadow missiles are made in Stevenage by MBDA. Each cruise missile costs an estimated £2m.
The Storm Shadow was originally developed as a project between the UK and France in the mid 1990s.
It was used in Iraq in 2003, while France, Italy and the UK used it in Libya in 2011.
The missiles have also been used to bomb Islamic State targets in Syria and Iraq.
Embassies shut over air attack fears
Earlier, the US and some other Western embassies in Kyiv closed amid fears Russia was preparing a major air attack on the Ukrainian capital.
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 Donald Trump Jr, the son of US President-elect Donald Trump, both warned that Mr Biden’s decision over Ukraine’s usage of long-range missiles could spark the start of a third world war.