Coleen Rooney has accused Rebekah Vardy of selling stories from her private Instagram account to tabloid newspapers.
Rooney, the wife of former Manchester United and England footballer Wayne, said she had suspicions about how the stories were ending up in the Sun newspaper.
She said she decided to block almost all of her followers from accessing her Instagram Stories to try to find the culprit.
This morning, in an Instagram post, she revealed that Vardy, the wife of England and Leicester striker Jamie Vardy, was the only person with access to her Stories.
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.
"To try and prove this, I came up with an idea. I blocked everyone from viewing my Instagram stories except ONE account. (Those on my private account must have been wondering why I haven't had stories on there for a while.)"
"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 response, Vardy denied that she was personally responsible and claimed that various people have had access to her account.
She said she was upset that Rooney had chosen to go public with her claims rather than speaking to her first.
Vardy said that she did not "need the money" and had nothing to gain from selling any stories to the newspapers.