Ukrainian air defence units are set up around the capital Kiev. ( Photo: AP)

Ukraine has been asking for months for long-range missiles, but support provided by Britain and other allies such as the US has previously been limited to shorter range weapons. 

Britain’s Defence Minister Ben Wallace said Britain was supplying the Storm Shadow missiles to Ukraine so they could be used within its territory, implying he had received assurances from Ukraine that they would not be used to target inside Russia. 

The Kremlin earlier said that if Britain provided these missiles it would require an adequate response from the Russian military.

Ukraine is expected to unleash a counteroffensive soon after six months of keeping its forces on the defensive.

Storm Shadows are air-launched long-range missiles, designed for attacks against high value targets such as hardened bunkers and have a range of more than 250 km.