Nicola Roberts' "heart is aching" following the sad news of her Girls Aloud bandmate Sarah Harding's passing.

Nicola Roberts and Sarah Harding (c) Instagram

Nicola Roberts and Sarah Harding (c) Instagram

The 39-year-old singer sadly lost her battle with breast cancer on Sunday (05.09.21) morning, and the 35-year-old singer admitted she is finding it difficult to "accept" that "this day has come".

Sharing a series of photographs of her and the late star from the day they shot the music video for 2002 mega-hit 'Sound of the Underground', Nicola wrote on Instagram: "I’m absolutely devastated and I can’t accept that this day has come. My heart is aching and all day everything we went through together has raced round my mind.

"Especially this last year since her diagnosis, as hard as the year has been, our new memories are strong in my heart.

"There are so many things to say and at first it felt to personal to put them here and then I remembered that there are so many other people grieving her too."

Nicola - who was also joined by Cheryl, 38, Nadine Coyle, 36, and Kimberley Walsh, 39, in the chart-topping girl group - added how Sarah "made" the band, and admitted it's "painful and utterly cruel" that she's gone.

She added: "A part of me or us isn’t here anymore and it’s unthinkable and painful and utterly cruel. She would have loved your messages today.

"Electric girl, you made us. You gave it everything and still with a smile.

"A white butterfly flew past my window this morning before I knew, it must have been you."

Nicola's tribute comes after Nadine took to social media to admit she is "absolutely devastated" following the tragic news.

She wrote on Instagram alongside a picture of Sarah: “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!!! (sic)”

At the time of writing, Cheryl and Kimberley are yet to publicly comment on Sarah’s death.

The devastating news was officially confirmed by Sarah’s mother, Marie Hardman.

She said: “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.”