South Korean girl group April has been rocked by allegations of bullying for months and three of its members have finally spoken up.

Former April member Hyunjoo, 23, who is at the centre of the controversy, released a statement on Sunday (April 18) on Instagram, detailing what happened when she lived in a dorm with the other five members of the group.

"The bullying began in 2014, when I was preparing for my debut, and continued until 2016, when I left the group. I was 17 years old at the time and had to live in a dorm while preparing to debut, so I had to spend 24 hours a day with the perpetrators in a place where there was no one I could lean on," she wrote.

"During those three years, I was forced to suffer because of violent actions and behaviour, ridicule, swearing and attacks on my character. And it was especially painful to bear groundless insults and attacks on the character of my precious grandmother, mum, dad and younger brother," she said, adding that her agency, DSP Media, knew of the incidents but did nothing.

She is still signed to the same agency, which has refuted her claims in a statement: "The contents of her post are a one-sided, distorted assertion that is far from the objective truth."

April members Chaewon and Yena also separately denied the allegations, which were first raised by Hyunjoo's younger brother in late February. A former classmate of hers from high school had also spoken up with further details of the bullying.

Yena said: "I always felt that one member was constantly pushing us away. When something happened to all of us, she thought of herself as the only victim. And even in a situation that arose by coincidence, she acted like we were the perpetrators."

Meanwhile, Chaewon addressed allegations that she was dating their manager, who turned a blind eye to the bullying, calling it "complete nonsense".

In Hyunjoo's post, she also touched on her suicide attempt in 2016, which she claimed was brushed aside by her agency and her group. "I fell into a darkness and could not see my way out, and I made an extreme decision, but it did not look as though they felt anything or felt even the slightest bit apologetic."

She eventually left April and has appeared in drama series such as The Witch Store (2019), as well as reality television show The Unit (2017) to form a temporary girl group, Uni.T.

"Using the reason that my agency prepared for me, I ended up leaving the group. And as a result, I had to face repeated malicious comments, ridicule and even the stigma of being a traitor."

Both she and her brother are being sued by DSP Media and all her work has been halted.

She said even though she was still traumatisedby the past, she was not giving up.

"From now on, I will no longer stand by without taking action to protect myself, my family and my acquaintances."