Jamie Lynn Spears has publicly come out in support of her sister Britney for the first time since the singer spoke about her controversial conservatorship in court.

The Zoey 101 star, 30, said she is “so proud” of her older sister, 39, for “using her voice” by speaking out against the arrangement.

In a video on Instagram Jamie Lynn also appeared to hit back at supporters of the #FreeBritney movement who have criticised her for not publicly backing her sister.

She said she has “only loved, adored and supported” her elder sibling, but chose to do so privately until she was ready to speak out herself.

“Maybe I didn’t support her 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 said in the clip.

In a court testimony last week Britney described the conservatorship – which allows her father Jamie to control many of her personal and financial decisions – as “abusive”.

She claimed she was forcibly given a contraceptive device to stop her having another baby and is not allowed to marry her boyfriend Sam Asghari.

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During video evidence at the Los Angeles hearing she said her medication was changed without her consent and compared her treatment and lack of privacy to being “sex trafficked”.

She called on the judge to end the controversial legal arrangement, which has been in place since she suffered a mental breakdown in 2008.

“I want my life back,” she told the court.

Her younger sister Jamie, who stars in the Netflix show Sweet Magnolias, said she has always encouraged her to change her lawyer – something Britney expressed publicly at the hearing.

“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,” she said.

“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. As long as she’s happy. So let’s keep praying. That’s all.”

On Friday, Britney posted on her Instagram to apologise to her fans for “pretending she was ok for the last two years”.

She said she was “embarrassed” to share her experiences and was waiting to make the revelations in court.

Jamie Spears and his lawyers say that the star and her fortune, which court records put at more than $50m (about £36m), remain vulnerable to fraud and manipulation and that he saved her from financial ruin.