Girls Aloud star Sarah Harding has died aged 39 after revealing a breast cancer diagnosis in August last year.
Harding's mother Marie shared the news on Instagram, saying her daughter "fought so strongly" against the disease "until her last day".
"It's with deep heartbreak that today I'm sharing the news that my beautiful daughter Sarah has sadly passed away," the message on Sarah's Instagram read.
"Many of you will know of Sarah's battle with cancer and that she fought so strongly from her diagnosis until her last day. She slipped away peacefully this morning," Marie wrote on Sunday (UK time).
"I'd like to thank everyone for their kind support over the past year. It meant the world to Sarah and it gave her great strength and comfort to know she was loved.
"I know she won't want to be remembered for her fight against this terrible disease - she was a bright, shining star and I hope that's how she can be remembered instead."
Sarah's Girls Aloud bandmate Nadine Coyle said she was "devastated" at the loss, writing on Instagram: "I can't think of words that could possibly express how I feel about this girl and what she means to me! I know so many of you will be feeling this way. For now I'm sending so much love to you!"
Meanwhile Sarah's former boyfriend, reality star Calum Best, wrote on Twitter: "Jesus this one hits home, so damn sad, so young.
"I hope you rest In peace Sarah, we had some crazy fun times and adventures. You will be so very missed. Sending so much love to your mom."
In her memoir Hear Me Out, Sarah wrote that she had been told the Christmas of 2020 would probably be her last. The pop star also admitted that she put off seeking medical attention when she first found lumps under her arm in 2019.
"One day I woke up realising that I'd been in denial about the whole thing," she wrote.
"Yes, there was a lockdown, yes, there was a pandemic, but it was almost as if I'd been using that as an excuse not to face up to the fact that something was very wrong."
Sarah found fame in 2002 after appearing on the television show Popstars: The Rivals, which formed the band Girls Aloud.
Spice Girl Geri Horner, who was a judge on the programme, tweeted: "Rest in peace, Sarah Harding. You'll be remembered for the light and joy you brought to the world."
Fellow judge Louis Walsh wrote: "She was always fun and the life and soul of the party. Anytime she came to Dublin in the early days, we went out to the Pod nightclub and would be the last to leave."