Sarah Harding pulled out of a performance of Ghost: The Musical on Monday night, mid-way through the show.

Harding, who plays the female lead Molly, did not return to the stage after the extended 41-minute interval, with understudy Kelly Hampson taking her place.

Sarah HardingSarah Harding was replaced mid-way through a performance of Ghost: The Musical on Monday

Producers told the audience that Harding was “indisposed”. Last month Harding pulled out of a number of performances just days after the show opened, due to a upper respiratory tract infection.

While no reason was given for Harding’s absence on Monday night, sources told The Sun it was due to ‘powerful painkillers she had been taking to ease a painful knee injury.’

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One audience member told the newspaper: “People stumbling home from the pub singing drunk would be better than what she did. She can’t sing and kept messing up her lines, slurring her words or speaking when it wasn’t her turn.

"There was one scene where she was speaking to her co-star Andy Moss and she started her line and he hadn’t even finished his.

“She also couldn’t move the pottery wheel across the stage. It had a brake on and she didn’t think to take it off so just dumped it. It was a big mistake."

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“She was absolutely awful," they added. "I’ve seen better performances from my daughter’s primary school. Her understudy saved the show. She was brilliant.”

On Twitter last night Harding hit back at the reports, but did not explain what had happened. “Some people should learn to get their facts right before making assumptions,” she wrote.