Tributes have poured in to the Girls Aloud singer Sarah Harding, who died at the age of 39 on Sunday.

       The mother of the pop star confirmed the news on Harding's Instagram page by thanking fans for their “strength and support”.

       Harding had been diagnosed with breast cancer in August 2020. She shared a picture on Instagram from her hospital bed, below.

       That September, she disclosed that she had first noticed something was “very wrong” during lockdown but that she just kept taking painkillers.

       She said she later realised she had been in denial. “I wasn’t exactly thinking straight, and all any of us had seen on the news was how terrible the situation in hospitals was during the pandemic,” she wrote in autobiography released earlier this year.

       Her mother Marie Hardman wrote on Instagram: “It’s with deep heartbreak that today I’m sharing the news that my beautiful daughter Sarah has sadly passed away.

       “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. 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.”

       Harding was born in Berkshire and raised in Stockport. She rose to fame alongside Cheryl Tweedy, Kimberley Walsh, Nicola Roberts and Nadine Coyle, when Girls Aloud was formed during the reality show Popstars: The Rivals in 2002. The group went on to enjoy huge success, with 21 UK Top 10 singles.

       They went on hiatus in 2009 and Harding embarked on an acting career. The band split in 2013. Harding had been largely out of the public eye since winning Celebrity Big Brother in 2017.

       Harding passed away on Sunday morning after several months of chemotherapy. As well as breast cancer, she also suffered with tumours in her brain and lung but she detailed in a memoir how both had shrunk with treatment.

       Earlier this year, the singer said she had been told by a doctor that she would probably not be alive this Christmas.

       In an extract of the memoir, titled Hear Me Out, Harding wrote: "In December my doctor told me that the upcoming Christmas would probably be my last. I don't want an exact prognosis. I don't know why anyone would want that.

       "Comfort and being as pain-free as possible is what's important to me now."

       She said she was "trying to live and enjoy every second of my life, however long it might be".

       "I am having a glass of wine or two during all this, because it helps me relax," she added. "I'm sure some people might think that's not a great idea, but I want to try to enjoy myself.

       "I'm at a stage now where I don't know how many months I have left. Who knows, maybe I'll surprise everyone, but that's how I'm looking at things."

       Harding said publicly revealing her diagnosis was "scary" but was also "the right thing to do".

       She said the support she had received had been "incredible", adding: "I've been inundated with lovely messages from my fans. I'm grateful beyond words for that."

       Tributes pour in

       Fans and celebrities posted on social media about their sadness at the news.

       Fellow Girls Aloud star Nadine Coyle said: “I am absolutely devastated!! I can’t think of words that could possibly express how I feel about this girl & 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!!!”

       Davina McCall, who hosted Pop Stars: The Rivals and Big Brother, wrote: "So so sad to hear about Sarah ... a star from the get go, hugely fun and outgoing yet also somehow fragile ... love to her family and friends."

       The singer and talent show judge Alesha Dixon said on Twitter: "A sad day! Such a shining star! Rest in peace beautiful Sarah."

       JLS star Oritse Williams, whose band emerged four years after Girls Aloud, shared a lengthy tribute online.

       He tweeted: "Heartbreaking to hear that Sarah Harding from Girls Aloud has just passed away after a long battle with cancer.

       "The times we met she was always so bubbly, such a big beautiful personality. My sincerest sympathies and heart goes out to Sarah's friends, family & band members."

       A tweet from the official account of Ant McPartlin and Declan Donnelly said: "Such sad news. RIP Sarah xx".

       Others paying tribute included the former Spandau Ballet member Martin Kemp, who tweeted: "Sarah Harding so sad, my heart goes out to all your friends and family and all your fans. Rest in peace!"

       The television presenter Fearne Cotton wrote: "Oh my gosh I'm so sorry to hear this. I'm sending your family so much love and strength.

       "She was always kind and so much fun to be around. I'm very sorry for your loss. Prayers and love to you."

       Calum Best, the reality TV star who was in a relationship with Harding between 2005 and 2006, spoke of the happiness he had with her.

       The television presenter Vernon Kay described Harding as "the driving energy in the room".

       "Very sad news," he tweeted. "From the moment Pop Idol finished GA were regularly on T4 and Radio1. Sarah was always the driving energy in the room... RIP."

       The television star Denise Van Outen commented on the Instagram post from Harding's mother, Marie, announcing her death.

       Van Outen wrote: "This is so heartbreaking. Rest in peace beautiful Sarah. Thinking of you all. Family and friends."