Natasha Giggs, who had an eight-year secret affair with the footballer while married to his brother Rhodri, was reportedly going to receive £50,000 to take part in the Channel 5 reality show.
"Baffles me how any paper can write an 'Exclusive' when I haven't spoken a word to them?!" she wrote on Twitter today.
Earlier on, a source had told The Sun: "Bosses are hoping she'll dish the dirt on life with Ryan. If I was Ryan I'd probably avoid the TV and the papers for January."
Producers apparently tried "in vain" to secure the 28-year-old for last summer's Celebrity Big Brother after she revealed her affair with Ryan in a newspaper.
The source added: "She's been someone that's been a must-get since the show was relaunched. She didn't sign up then but she's agreed to do it now all that stuff has died down a bit."
Former EastEnders actress Natalie Cassidy and Loose Women star Denise Welch have also signed up for the show, the report adds.
The source also claimed that it is "amazing" how many US stars are considering offers for Celebrity Big Brother, which returns to its traditional slot in the New Year.
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