The 34-year-old called Katie 'brash and common' and suggested that the businesswoman hit on Danny Cipriani while she was still in a relationship with him.
JENNIFER LAWRENCE DESCRIBES LEAKED NUDE PHOTOS AS A 'FLAGRANT VIOLATION'
Never one to stay quiet, Katie has hit back. Writing in her British magazine column, she said: "Apparently being a glamour model was the wrong job for me because I have no hips or curves.
"So says one of my fellow page 3 girls from back in the day. Yes, Kelly Brook has a book out – and it suggests she's followed my career closely."
Mum-of-five Katie insisted that no matter what your background is, nothing should stop you doing the job you love.
She continued: "Being common, posh or whatever your background is shouldn't stop you from living your dream!"
Katie finished by insisting that she has no problem with Kelly, but said: "Haters gonna hate… But I'm gonna shake it off."
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Meanwhile, Kelly caused outrage yesterday when she appeared on This Morning to promote her book, and appeared to laugh off the fact she hit ex boyfriend Danny, 26.
Users on Twitter hit back at her 'trivialising domestic violence', with one raging: "Glad she finds [it] so funny! A punch is abuse no matter what gender's doing it."