Ferne McCann has been accused of launching a "vile" attack on Billie Shepherd and Sam Faiers by their mum Suzie Wells amid alleged "leaked" voice notes.
Suzie, 53, has said that she is "hurt and upset" after making the discovery.
It comes after Sam and Ferne's increasingly strained relationship over recent years following their departure from The Only Way Is Essex.
Taking to her Instagram Stories, Suzie shared the leaked voice notes - which were allegedly sent by Ferne just months after Sam gave birth to her third baby Edward - and wrote: "So after a few days of hurt and upset I can no longer sit back and say nothing.
"This vile voice note has been circulating social media, and now Press articles calling it a 'Fued' [sic] which it is not. This has come as a complete shock to myself and my family.
"Ferne has always been a very close family friend to all of us for over the past 20 years. It appears this voice note was sent just weeks after Samantha gave birth back in May.
"Since this voice note has surfaced more have been sent - very upsetting nasty things. We are as shocked as you are! Nobody should ever speak about their friends like this ever!
"My girls are my absolute everything and I'll do anything to protect them. I don't have anything to say on the matter."
In the voice note, Ferne appears to say: "Sam Faiers is a fat c***. Her thighs are so big and I looked really skinny today and... yeah."
It is not known what triggered the voice note or who Ferne is said to have originally sent it to.
Sam is believed to have unfollowed and blocked Ferne since hearing the message.
A source told the Mirror: "Naturally Sam is incredibly hurt and upset by these comments, especially from someone she considered to be a good friend, she's at a loss as to why Ferne has decided to speak out about her in such a derogatory way."
The Mirror has reached out to Ferne's rep for comment. Ferne has not yet responded to Suzie's Instagram Story.