The Irish rockers played a handful of songs during the concert at the Mercedes-Benz Arena in Berlin, Germany, on Saturday (01Sep18), then launched into a performance of their track, Red Flag Day.

According to concertgoers, halfway through the song, Bono lost his voice.

The band then attempted to play Beautiful Day, before realising the 58-year-old was unable to sing. The rockers then left the stage, telling fans they'd be back in 15 minutes.

In a video shared on Twitter, Bono is seen pausing the show, telling the crowd that "something's happened" and that they "cannot go on."

"So sorry, thank you," the singer says in the video before clearing his throat. "Before we left the dressing room, I was ready to sing for you. Something's happened and I think we cannot go on. It's not right for you... I'm sure this is not a big, big problem, but I'm going to have to do something.

"So... if people want to go home, that's fine. We'll play another show for you some other time. If you want to stay, we're gonna have to break for, I don't know, 10, 15 minutes. I'll go find out what's happening," he added, before reportedly blaming the smoke machines for affecting his voice.

The disappointed fans were later told that the band were forced to cancel the show.

U2 later took to their website to apologise, and revealed that Bono was to receive medical attention.

“We're so sorry for tonight's cancellation. Bono was in great form and great voice prior to the show and we were all looking forward to the second night in Berlin, but after a few songs, he suffered a complete loss of voice," the statement read.

"We don't know what has happened and we're taking medical advice," it added.