Starmer is accused of weakening support for Ukraine

A Pentagon spokesman said on Thursday that the US believes the use of the missiles would represent an “escalation” and provoke a Russian response against Ukraine's Western allies.

Zelensky's criticism of Britain came after Sir Keir suggested at the NATO summit last month that Ukraine could be allowed to use the missiles.

A Downing Street spokesman later said the ban on the use of Storm Shadows in Russia imposed by the previous Conservative government remained in place.

A spokeswoman for the British Ministry of Defense said on Sunday that there had been “no change in Britain's position.”

However, four former Conservative defence ministers told The Telegraph that Sir Keir should help Ukraine more after his then defence secretary John Healey said Britain's support would be an “iron guarantee” under the Labour Party.

Sir Michael Fallon, who was defence secretary in Theresa May's government, said: “It cannot be right to let Putin hit a children's hospital with glide bombs from several kilometres across the border while denying Ukraine the ability to defend itself with long-range missiles such as Storm Shadow.”

Sir Ben Wallace, who served under Boris Johnson, said: “Time and again those who want to do nothing have used the excuse of 'escalation'.

“They used it before the conflict, they used it when we supplied them short-range anti-tank missiles, they used it when we supplied them tanks.

“The reality is that it is the appeasers who use this language and Ukrainians suffer from it all the time. Storm Shadows has made a real difference in Crimea, which Russia already considers sovereign Russian territory, without causing any escalation.”