SINGER Sam Smith has cancelled their concert at Glasgow’s Hydro just hours before it was due to start.

The concert was set to take place at the Ovo Hydro on Thursday, May 25 – after having been delayed from April 22.

The artist took to Instagram to say they are “heartbroken” and feel if they keep singing, they will do permanent damage to their voice.

A spokesperson said: “Doctors have advised due to a vocal cord injury, Sam must have complete vocal rest.”

Refunds will be available for the cancelled show in Glasgow, as well as in Manchester and Birmingham.

Smith previously delayed the gig, which had been due to take place on April 22, with just one day's notice.

They told fans on April 21 that a lot the tour team had "been hit with a virus".

“I want to give you the best version of Gloria [the name of their latest album] the tour and at the moment that’s not possible. It was also really important to me that we had another date to move this to straight away," Smith said at the time.

There has not been any suggestion that the newly cancelled show will be rescheduled.

Fans have already taken to Twitter to express their frustration at the late cancellation. 

"Are we going to get the money back tha we spent on hotels and train tickets to come and see you?" one fan wrote.

"I feel exactly the same," a second added. "I've paid for flights, hotels and a boat to see them twice after it being rescheduled last time! Just ridiculous to cancel it such last minute. I won't be able to get my money back."

At Wednesday's concert in Manchester, fans were disappointed as Sam Smith left the stage after just four songs. They took to Instagram to apologise for the situation, citing vocal issues.