A woman has told an inquiry that she was sexually assaulted with a double-barrelled shotgun at a New South Wales Central Coast yoga ashram, and was not sure the man who did it would not pull the trigger.

The Royal Commission into Institutional Responses to Child Sexual Abuse is investigating allegations of sexual and physical abuse made against the former spiritual leader and director of the Satyananda Yoga Ashram in New South Wales, Swami Akhandananda Saraswati, in the 1970s and 80s.

The 57-year-old woman known as Shishy cared for children who were separated from their parents at the ashram where family relationships were broken down.

Shishy met Akhandananda when she was 16 and he was aged about 22. She was initiated at the age of 19 to a full swami and went to live at the Central Coast ashram, sleeping in the same quarters as Akhandananda.

The commission has heard that Akhandananda's behaviour towards her became increasingly threatening as the years passed, and he began cutting at her vagina with nail scissors and threatening her with a pocket knife.

He also used the pocket knife to cut out her moles, at times leaving deep wounds.

"He wouldn't allow me to get medical attention so I sewed those two [cuts] up with fishing wire," she said.

Shishy said she was "terrified" when Akhandananda sexually assaulted her with a double-barrelled shotgun, in the lead up to her fleeing the ashram in 1984.

"I felt like if I moved or did anything other than receive it that I wasn't 100 per cent sure that he wouldn't fully pull the trigger," she said.

Shishy has told the inquiry that she did not procure girls for sex at the yoga ashram but was present when two young girls were sexually assaulted.

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Child abuse royal commission: Woman assaulted with double-barrelled shotgun at Satyananda Yoga Ashram, inquiry hears