Sir Keir Starmer has spoken to Ukraine’s president Volodymyr Zelensky as his country’s power grid faces bombardment by Russian forces.

Mr Zelensky characterised the latest attack by Vladimir Putin’s forces as “yet another act of Russian air terror targeting Ukraine’s civilian infrastructure, involving over 90 missiles and nearly 100 drones”.

Russia’s renewed attack on Ukraine’s power grid, the second in less than two weeks, has added to fears the Kremlin is hoping to cripple its foe’s power generation ahead of winter.

One million homes have lost power in the war-torn nation, according to Ukrainian officials.

Downing Street described the Russian strikes as “egregious”, adding that the Prime Minister characterised them as “systematic” and “depraved” when speaking to Mr Zelensky.

Amid the attacks, Mr Zelensky “expressed gratitude for the UK’s unwavering support, including the commitment to provide at least £3 billion annually for Ukraine’s needs” in his call with the Prime Minister.

In a fresh signal that British Storm Shadow missiles are likely being used by Kyiv, the Ukrainian president added: “We discussed advancing our defence co-operation and strengthening Ukraine’s long-range capabilities.”

UK authorities will not be drawn into confirming it has given Ukraine permission to use the weapons to strike targets inside Russia.

No 10 would only say that “both leaders underlined the importance of putting Ukraine in the best possible position ahead of another challenging winter of conflict”.

The Prime Minister has previously said revealing such information would only benefit Mr Putin, who has ramped up Russia’s arsenal in recent weeks by launching a new long-range ballistic missile at Ukraine.

Chunks of debris from Storm Shadow missiles are reported to have been found in Russia’s Kursk region, which borders Ukraine.

Of his call with Sir Keir, Mr Zelensky added: “We also discussed Ukraine’s potential participation in the upcoming JEF (Joint Expeditionary Force) summit in Tallinn next month and agreed to expedite preparations for the historic Partnership Agreement marking 100 years of Ukraine–UK relations.”

Elsewhere, US President Joe Biden’s administration has urged Ukraine to lower its age of conscription from 25 to 18 to help expand its pool of fighting age men.