Space-travel fans are familiar with the phrase: "Houston, we have a problem."

The American city is where Nasa runs a space centre that maintains contact with astronauts during missions.

On Wednesday, the alert sounded, this time from British rock group The Who who were performing in Houston.

According to USA Today, the audience had heard only eight songs when singer Roger Daltrey, 75, said: "I think I should quit while I'm ahead."

He had lost his voice.

After he walked off the stage, there was a short break before lead guitarist Pete Townshend, 74, came out to issue an apology, saying Daltrey "cannot actually speak now".

"Apparently, before the show, he saw a doctor, and, you know, he's been singing great through this tour. I don't know what's going on. He has been on top of his game."

The Who, who are on a North American tour, have also postponed a show in Denver.

But there is happier news for fans, with the rockers set to release their first new album in 13 years on Nov 22.