Ukraine needs “more and more” arms from the West to “keep the pressure up on Russia” after regaining swathes of territory from Moscow, the former head of the British Army has said.

Lord Dannatt said Russian troops have “pretty much turned and fled” from the Kharkiv area, representing a “significant reverse” of their position.

But while this is a “great success” for the Ukrainians, he said they continue to need “more and more” Western arms and ammunition in order to “keep the pressure up”.

“We are witnessing some incredible scenes,” he told Sky News.

“Although the Ukrainians have made significant advances, there’s a lot of their country still in Russian occupation. So there’s a long way to go.”

It comes as Ukraine has managed to recapture Russian-occupied areas in the Kharkiv region.

Significant quantities of weapons and munitions were left behind as Moscow hastily withdrew its troops to prevent them from being surrounded.

Lord Dannatt said Russia was responding to Ukraine’s recent success in a “typically heavy-handed way”, and “blindly lashing out” by targeting the country’s power supplies.

In Kharkiv, the few pedestrians who could be seen outside on Sunday night used torches or mobile phones to guide them through darkened streets following the bombardment of a power station on the city’s western outskirts.

The former army chief said: “They (Russian officials) know that they’ve had a significant reverse on the battlefield, so they’re lashing out in other ways to try and restore their position.

“The resistance and the attitude that you’re seeing from the Ukrainian people is ‘yes, no, we don’t like the darkness, we don’t like the lack of water, but we will win through, they will not break our spirit’.

“And I think that is the other critical issue. Morale in Ukraine and morale amongst the Ukrainian forces is sky-high.”