Ukraine has fired the UK’s storm shadow missiles into Russian territory for the first time, reports claim.

A Western official familiar with the matter told Bloomberg that the UK had approved of the strikes in response to Russia deploying North Korean troops to fight in the Ukraine war.

The UK has not officially announced it has given Kyiv permission to use these weapons – which have a range of up to 155 miles – into Russia.

PM Keir Starmer refused to get into operational details around the missiles on Monday. He told journalists at the G20 summit in Brazil: “The only winner, if we were to do that, is Putin.”

The reports follow claims that the US has also given Ukraine the go-ahead to use American long-range missiles known as ATACMS, which can reach targets up to 190 miles away, against Russia.

The US’s change in policy allegedly came after Moscow recruited Pyongyang soldiers to fight on its behalf, a move widely perceived as an escalation by the west.

The UK and France, which make the storm shadow missiles together, indicated earlier this year that they may look at lift restrictions on using the weapons if the US does the same.

But critics have expressed fears this may bring the west into direct conflict with Russia, especially as Vladimir Putin’s spokesperson said the US lifting restrictions on ATACMS would trigger a “rise in tensions”.

The Russian president lowered his country’s threshold for using nuclear weapons, on the same day Ukraine allegedly fired American-made ballistic missiles into Russia for the first time.

Starmer said earlier this week that Ukraine’s allies need to “double down” on support for the beleaguered country.

He said: “I’ve been really clear for a long time now we need to double down.

“We need to make sure Ukraine has what is necessary for as long as necessary, because we cannot allow Putin to win this war.”