Jamie Lynn Spears has come out in support of her sister Britney's condemnation of her conservatorship.

The older Spears sister testified in court about the conditions of her conservatorship on June 23, calling the situation 'abusive,' and criticising her father and the other conservators who've managed her life and affairs since 2008.

The singer also detailed how she was refused permission by her guardians to remove an IUD and forced to take other medications – including lithium – and alleged that she isn't permitted to have any more children or get married.

Actress and singer Jamie Lynn posted on Instagram yesterday, explaining to her followers that she had waited to speak out until after Britney had.

She spoke of how she has "only loved, adored and supported" her older sister, but had done so privately, not publicly, and took a swipe at those who had criticised her in the past for not engaging with the #FreeBritney movement.

"Maybe I didn’t support her the way the way the public would like me to with a hashtag on a public platform, but I can assure you I’ve supported my sister long before there was a hashtag and I’ll support her long after," she explained in a series of stories on her Instagram page.

"I’m so proud of her for using her voice. I’m so proud of her for requesting new counsel like I told her many years ago — not on a public platform but just in a personal conversation between two sisters. If ending the conservatorship and flying to Mars or whatever the hell else she wants to do to be happy – I support that 100% because I support my sister. I love my sister. Always have, always will."

Many other celebrities have publicly declared their support for Britney Spears in the wake of her testimony, including her former Mickey Mouse Club castmate and pop-star contemporary Christina Aguilera, who posted an open letter to Spears on her Twitter account.

"These past few days I’ve been thinking about Britney and everything she is going through," she wrote. "It is unacceptable that any woman, or human, wanting to be in control of their own destiny might not be allowed to live life as they wish."

She continued: "While I am not behind the closed doors of this very layered & personal yet public conversation – all I can do is share from my heart on what I’ve heard, read and seen in the media. The conviction and desperation of this plea for freedom leads me to believe that this person I once knew has been living without compassion or decency from those in control."

Read the full thread below.

These past few days I’ve been thinking about Britney and everything she is going through.

It is unacceptable that any woman, or human, wanting to be in control of their own destiny might not be allowed to live life as they wish. pic.twitter.com/NRhNwcJaD3

— Christina Aguilera (@xtina) June 29, 2021

Other celebrities who have come out in support after Spears' testimony include 90s pop contemporaries like Mariah Carey and Brandy. Spears' ex-boyfriend Justin Timberlake, who already issued an apology to Britney in the wake of the Framing Britney Spears documentary, also tweeted in support of her last week.

After what we saw today, we should all be supporting Britney at this time.

Regardless of our past, good and bad, and no matter how long ago it was… what’s happening to her is just not right.

No woman should ever be restricted from making decisions about her own body.

— Justin Timberlake (@jtimberlake) June 24, 2021