Britain has not yet ruled out giving Ukraine Harpoon cruise missiles — which can hit targets deeper inside Russia.
Hundreds of the weapons, due to be retired from the Royal Navy this year, are available.
The UK’s Harpoon cruise missiles have a maximum range of 240km – six times further than the most powerful GMLRS missiles Britain has so far supplied.
They could target launch sites that Russia uses to strike Ukraine’s energy infrastructure.
Defense Secretary Baroness Goldie said: “The UK has not ruled out providing longer-range weapons to counter Russia’s indiscriminate mass targeting of civilian infrastructure.”
He insisted that British weapons were used “in accordance with international humanitarian law”.
Baroness Goldie added: “We are in daily contact with the Ukrainian government and it is clear that the equipment provided by the UK is for the defense of Ukraine.”
The UK has led the way by pledging 14 Challenger 2 tanks over thousands of anti-tank, anti-ship and anti-aircraft missiles.
A defense source said it could donate Harpoons or buy missiles from third countries.
Former Prime Minister Boris Johnson last night said the West should provide longer-range aircraft.