The wife of former England captain Wayne Rooney made the sensational claim in a Twitter post, in which she said she had devised an elaborate scheme to establish which of her followers on the social media platform was passing information to the newspaper.
Vardy, the wife of Leicester City striker Jamie, denied deliberately leaking any stories and suggested her Instagram account had been hacked.
Her spokeswoman told The Independent she was consulting with her legal team over the accusation.
Rooney claimed she worked out it was I’m A Celebrity ... Get Me Out Of Here! star Vardy, following a process of elimination.
She wrote: “For a few years now someone who I trusted to follow me on my personal Instagram account has been consistently informing The Sun newspaper of my private posts and stories.
“There has been so much information given to them about me, my friends and my family – all without my permission or knowledge.
“After a long time of trying to figure out who it could be, for various reasons, I had a suspicion.”
Rooney, 33, said she “came up with an idea” to try to prove her theory that it was Vardy, and that she blocked everyone apart from her from seeing her Instagram stories.
She added: “Over the past five months I have posted a series of false stories to see if they made their way into The Sun newspaper.
“And, you know what, they did! The story about gender selection in Mexico, the story about returning to TV, and then the latest story about the basement flooding in my new house.
“It’s been tough keeping it to myself and not making any comment at all, especially when the stories have been leaked; however, I had to. Now I know for certain which account/individual it’s come from.
“I have saved and screenshotted all the original stories which clearly show just one person has viewed them.
“It’s ... Rebekah Vardy’s account.”
In reply to the post – which instantly went viral – Vardy denied ever speaking to journalists about the mother-of-four and said she was disgusted at the allegation – “especially when I’m heavily pregnant”.
She wrote: “As I have just said to you on the phone, I wish you had called me if you thought this.
“I never speak to anyone about you as various journalists who have asked me to over the years can vouch for.
“If you thought this was happening you could have told me & I could have changed my passwords to see if it stopped. Over the years various people have had access to my insta & just this week I found I was following people I didn’t know and have never followed myself.
“I’m not being funny but I don’t need the money, what would I gain from selling stories on you?
“I liked you a lot Coleen & I’m so upset that you have chosen to do this, especially when I’m heavily pregnant. I’m disgusted that I’m even having to deny this. You should have called me the first time this happened.”
She ended the post with a broken heart emoji.
Her spokeswoman has since told The Independent she is consulting with her legal team over the accusation. “Such a shame that Coleen didn’t just call,” she added.
The Sun said it was unlikely to comment on any story about its journalists’ sources – but by late morning it appeared to have removed all three stories made up by Rooney from its website.
The spat comes after then England manager Roy Hodgson denied rumours of a rift between the two women when their husbands were playing together for the national team in the 2016 European Championships.
But if it seemed like a miserable situation for all the main protagonists, there was at least one happy note. A chap going by the name Dave had first suggested Rooney turn detective.
In January she had tweeted that she had become aware that someone in her close circle was betraying her to the press.
“Make a false story tell ppl different things see which 1 comes out = find the culprit,” wrote Dave.
Whether Rooney saw the tweet and followed the advice remains to be confirmed but by mid-afternoon on Wednesday, Dave had taken credit anyway. His own Twitter biography had been changed: “uk football darts #mufc poker player, Detective who recently solved the coleen rooney vs rebekah vardy case.”
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies