Irish rock band U2's Bono and The Edge performed a surprise concert for Ukrainians at a subway station in the capital Kyiv on Sunday.

Frontman Bono and guitarist The Edge played some of the band's biggest hits as well as other classics such as "Stand By Me," - adapted to "stand by Ukraine" - as could be seen on videos on Ukrainian broadcasters and social media.

"President [Volodymyr] Zelensky invited us to perform in Kyiv as a show of solidarity with the Ukrainian people and so that’s what we’ve come to do," the band wrote on its official Twitter feed.

"Your president leads the world in the cause of freedom right now ... The people of Ukraine are not just fighting for your own freedom, you're fighting for all of us who love freedom," Bono told a crowd of up to 100 gathered inside the Khreshchatyk metro station. He was referring to Ukrainian President Volodymyr Zelenskyy.

Russia invaded Ukraine on Feb. 24, pressing toward Kyiv before withdrawing its forces from near the capital at the end of March to concentrate its firepower on eastern Ukraine.

Russia, which calls its action in Ukraine a "special military operation," continues to carry out missile strikes across Ukraine. However, some life has returned to Kyiv even though air raid sirens sound regularly.

Bono rallied the crowd between songs during his performance.

"This evening, 8th of May, shots will ring out in the Ukraine sky, but you'll be free at last. They can take your lives, but they can never take your pride," he said.