LOS ANGELES - Pop star Britney Spears may have finally broken free of her father's conservatorship in November last year, but she has been trading barbs across social media platforms with another relative: younger sister Jamie Lynn.

It all began when Jamie Lynn, 30, gave an interview on American television show Good Morning America to promote her upcoming memoir, Things I Should Have Said, on Jan 13.

The interviewer highlighted that Jamie Lynn's book described Britney's behaviour as "erratic", "paranoid" and "spiralling" prior to the singer being placed under conservatorship in 2008.

But the younger Spears said that she had always been her sister's biggest supporter.

"I've only ever loved and supported her and done what's right by her," Jamie Lynn, an actress in Netflix drama Sweet Magnolias since 2020, said tearfully.

In the wake of the interview, Britney, 40, took to Twitter to question her sister's motives in speaking about her. "She was never around me much 15 years ago at that time… so why are they even talking about that unless she wants to sell a book at my expense?" she said in a post on Jan 14.

On the same day, Jamie Lynn responded on Instagram to what she described as Britney's "vague and accusatory" posts, saying, "It's become exhausting when conversations and texts we have in private don't match what you post on social media."

Britney shot back on Jan 15, saying on Twitter that her younger sister had "stooped to a whole new level of low". She added: "Please stop with these crazy lies for the Hollywood books" and "I do know only a scum person would make up such things about someone".

Jamie Lynn did not directly reply to these accusations. Britney followed up with another tweet on Sunday (Jan 16), clarifying that she did not mean to call her sister a "scum person": "When I said only a scum person would make up things like that about someone, I could have sworn I said 'but you're not'".

The Toxic singer then noted in the post, which was formatted as an open letter to Jamie Lynn, that "(you and the rest of our family) treated me like nothing and that's not even half of it" but nevertheless declared her love for her sister, saying "just know I love you".

In an Instagram story later that day, as archived by news outlet Buzzfeed, Jamie Lynn begged her sister to give her a call and settle the matter once and for all. "I have attempted many times to speak to you directly and handle this privately", she said. "This is embarrassing and has to stop."