Madonna has likened Britney Spears' conservatorship to "slavery".
The 62-year-old singer has sent her support to the "Toxic" hitmaker - whose personal and business affairs have been controlled since 2008 - and called her situation a "violation of human rights".
She wrote on her Instagram Stories: "Give this woman her life back. Slavery was abolished so long ago!
"Death to the greedy patriarchy that has been doing this to women for centuries.
"This is a violation of human rights!"
Madonna also vowed to free the 39-year-old singer - who claimed in court last month her conservatorship is "abusive" - likening her situation to being in prison.
She added: "Britney we coming to Get you out of jail [sic]!"
Madonna is not the only star to throw her support behind Britney, who she famously kissed on stage at the 2003 MTV Video Music Awards during a performance of her songs 'Like A Virgin" and "Hollywood".
Christina Aguilera, who was also part of the performance, recently hit out at Britney's "unacceptable" conservatorship.
The 40-year-old singer - who starred alongside the "Gimme More" hitmaker in Disney's "The Mickey Mouse Club" variety show in the '90s - claimed Britney "deserves all of the freedom possible to live her happiest life".
In a series of tweets, Christina wrote: "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.
"To be silenced, ignored, bullied or denied support by those "close" to you is the most depleting, devastating and demeaning thing imaginable. The harmful mental and emotional damage this can take on a human spirit is nothing to be taken lightly.
"Every woman must have the right to her own body, her own reproductive system, her own privacy, her own space, her own healing and her own happiness.
"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.
"To a woman who has worked under conditions and pressure unimaginable to most, I promise you she deserves all of the freedom possible to live her happiest life."
And the "Beautiful" hitmaker also urged others to "support" Britney.
She added: "My heart goes out to Britney. She deserves all the TRUE love and support in the world."
Spears spoke in court last month about being "traumatised" and "depressed" under her conservatorship.
She said: "I truly believe this conservatorship is abusive. I don't feel like I can live a full life. In the meantime, I want this therapist to come to my home, I'm not willing to go to Westlake ... They set me up by sending me to the most exposed places. I need your help."