Children were groomed and physically and sexually abused at a yoga retreat on the New South Wales Central Coast, a witness at a child sex abuse inquiry has said.

Bhakti Manning will give evidence at the Royal Commission into Institutional Responses to Child Abuse over the response of the Satyananda Yoga Ashram to allegations of child sexual abuse by the Ashram's former spiritual leader in the 1970s and 1980s.

Ms Manning was just 14 years old when she first attended the retreat located in bushland at Mangrove Mountain in 1974 with a group of other children, some as young as five, who were separated from their parents there.

"We were children who were groomed to be used by those who had power," she said.

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"There were methods of making us feel we were special.

Bhakti Manning claims she was sexually abused at the Satyananda Yoga Ashram in the 1970s. ( ABC News )

"Not only was there sexual abuse, we worked for nothing - our whole lives were controlled."

According to Ms Manning, spiritual teachings were used as a form of control.

"Surrender and obedience to the guru was the highest quality," she said.

"Reincarnation - we're connected by lives before and we'll be connected. There's no escape.

"Pleasing the guru - you can never be perfect, so you're always failing.

"Family - you give up your family and this is your family. If you speak up you are disloyal, you are a traitor."

Ms Manning claimed she was abused by two Indian swamis in Australia, including the Ashram's director, Swami Akhandananda Saraswati.

"It takes everything from you," she said.

"You're being built up and encouraged and told how wonderful you are and how much faith they have in you, and under that you're being undermined and abused and used."

Akhandananda charged with sex offences

Akhandananda was charged in 1987 with more than 35 sex offences against four teenage girls.

Before he went to trial in 1980, there were changes to NSW laws and the charges were reduced to the much lesser offences of acts of indecency.

Akhandananda was jailed in 1989 but his conviction was overturned when his lawyers argued the indecency charges were only laid to avoid the statute of limitations.

He died six years later.

The Satyananda Yoga Ashram would become the Australian headquarters of a global yoga movement started by an Indian guru, Swami Satyananda Saraswati, in the 1950s. ( Facebook )

The Ashram would become the Australian headquarters of a global yoga movement started by an Indian guru, Swami Satyananda Saraswati, in the 1950s.

Ms Manning said Saraswati was "charismatic, intelligent and powerful".

"In Australia, I was abused by two Indian swamis, then in India by the founder - Swami Satyandanda," she said.

"In India, the founder manipulated the lives of girls and women where he saw fit."

Saraswati died in 2009.

Ashram apologises on Facebook

The ashram on the central coast has changed its name to Mangrove Yoga Ashram but still follows the Satyananda movement.

Earlier this year, it issued an apology to abuse victims on Facebook.

"In response to these comments and on behalf of Mangrove Yoga Ashram, we would like to acknowledge the events of the past and offer an apology to the children and adults whose lives were affected by the abuse and misconduct of those in charge of the ashram in the late '70s and early '80s," the apology read.

"It was a period of devotion, trust and inspiration, which for many ended in disillusionment and great pain.

"No doubt the failure of the ashram to publicly acknowledge these events has added to the pain and prevented many from finding a path to healing."

Bhakti Manning said the apology was unsatisfactory.

"The ashram today only wants to know and hear about the abuse by Swami Akhandananda," Ms Manning said.

"Swami Satyananda is worshipped as though he's a saint."

The inquiry will also investigate the systems, policies and procedures in place at the Ashram between 1974 and 1989, and currently, in relation to raising and responding to allegations of or concerns about child sexual abuse.

Up to nine alleged victims will testify over the two week hearing which begins in Sydney on Tuesday.