'Deeply humbling': UK PM Rishi Sunak makes 1st official visit to war-torn Ukraine

British Prime Minister Rishi Sunak on Saturday used his first visit to Kyiv to announce a major new air defence package, as the country celebrated retaking the southern city of Kherson.

Kyiv meanwhile said it was checking the authenticity of video footage Moscow says shows surrendering Russian soldiers being executed.

"I am here today to say that the UK will continue to stand with you... until Ukraine has won the peace and security it needs and deserves," Sunak told journalists at a news conference with President Volodymyr Zelensky.

The British leader said the new package was worth £50 million ($60 million).

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This comprises "125 anti-aircraft guns and technology to counter deadly Iranian-supplied drones, including dozens of radars and anti-drone electronic warfare capability," said a Downing Street statement.

It follows more than 1,000 new air-defence missiles announced by the British Defence Secretary Ben Wallace earlier this week.

"It is deeply humbling to be with you in your country today. The courage of the Ukrainian people is an inspiration to the world," Sunak told his host.

Ukraine had requested more air defence systems to defend against Russia's bombardment of its energy infrastructure.

"In years to come we'll tell our grandchildren of your story, how proud and sovereign people stood up in the face of an appalling onslaught, how you fought, how you sacrificed, how you prevailed," said Sunak.

In response, Zelensky praised a "meaningful and useful visit for both our countries", during which the two leaders had discussed how to protect "European and Ukrainian energy security" and defence cooperation.

"With friends like you by our side, we are confident in our victory," he added on Twitter.

And in his evening address, Zelensky thanked Sunak "for your willingness to defend freedom even more strongly with us".