Sir Keir Starmer has said the UK's "cast-iron" support for Ukraine will continue, as he makes a final trip to the country as prime minister.

He will meet Ukrainian President Volodymyr Zelensky in the capital Kyiv later on Thursday, ahead of Andy Burnham's installation as Labour leader and PM.

In comments ahead of his trip, Sir Keir said the "fortitude" of the Ukrainian people since Russia's full-scale invasion in February 2022 had "preserved the security of Europe".

In his statement, Sir Keir highlighted Britain's contribution to the Ukrainian war effort during his two years in Downing Street.

Today is Sir Keir's last day as leader of the Labour Party, with Andy Burnham set to be declared leader on Friday, before meeting the King to be formally invited to form a new government as prime minister on Monday.

Sir Keir has overseen the signing of a 100-year partnership between the two countries, aimed at fostering closer defence and trade ties, and has led efforts to establish a future peacekeeping force.

"When I became prime minister, I knew the UK must not simply stand with Ukraine in the moment, but help build the foundations of its long-term security and success," he said.

He said the UK had invested more in defence, as well as "leading the way in the war fighting technologies of the future".

Sir Keir added: "And we have brought others with us on that journey. As we showed at the G7 and Nato summits, in recent weeks, the UK and its allies are absolutely united against Russian aggression."