Mrs Rooney, married to ex-England captain Wayne Rooney, posted a message on Twitter claiming posts from her Instagram stories were being leaked by one of her followers.
She went on to state it was Mrs Vardy’s account, writing: "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.
"To try and prove this, I came up with an idea, I blocked everyone from viewing Instagram except ONE account."
Mrs Vardy responded on social media, claiming she was seeking legal advice.
“Can’t believe I’m even having to write this,” she said with accompanying message. “I’m pregnant & on holiday & am at a loss to why she would do this. I’m now having to take legal advice as I can’t deal with this stress myself when I’m this pregnant.”