Allegations of non-Indigenous interference with Indigenous art have shaken up the APY Arts Centre Collective (APYACC), one of Australia's leading Indigenous arts organisations.

The claims, made by a number of Aboriginal painters and supported by incriminating video evidence, have caused widespread controversy surrounding the upcoming Ngura Pulka - Epic Country Exhibition at the National Gallery of Australia.

Over the course of four months, The Australian conducted an investigation that revealed troubling allegations.

Five Indigenous artists who worked at the APY Arts Centre Collective's Adelaide studio claim non-Indigenous staff members had a significant impact on Indigenous artworks.

Recently filmed footage shows Rosie Palmer, the non-Indigenous manager of Tjala Arts in the outback, painting on the canvas of Yaritji Young, a highly respected Australian painter and winner of the Wynne Prize alongside her sisters.

In the video clip, Ms Palmer surveys the painting with another white staffer, who says: "could it do with another rockhole there, or is that going to be too circular?"

Later, Ms Palmer says to her colleague, "can I juice this one up a little bit?" before painting red circles on Young's canvas, which is meant to represent the artist's "Tjukurpa", or sacred stories.

Ms Palmer initially denied working directly with Young.

When shown a still image from the video of her holding a brush, said: "I absolutely deny that I am painting in this photo. I am holding an unused brush and a bucket of pre-prepared red wash that Yaritji has already used to lay down the tjukula ­(rockhole) and passed back to me."

Palmer then changed her story, via lawyers, to claim she was assisting the artist with "background wash … at the artist's discretion".

A member of O'Meara's APYACC board, Sally Scales, an Anangu artist herself, insists "there's no intervention" by non-Indigenous staff in the works of APY artists and even claims that criticism of O'Meara is sexist, even though majority of the allegations are from women.

Paul Andy, an Anangu artist, is among those who have accused non-Indigenous staff of tampering with Indigenous artwork at the APYACC's Adelaide studio.

Mr Andy alleged that Skye O'Meara, the general manager of APYACC, painted over his design on a piece titled "Emu Dreaming," which was intended to depict his grandfather's Tjukurpa.

"That must be her dreaming," he said. "When there were other (artists) there, she would do the same for those other artists as well," Mr Andy claimed.

"You know that what she is doing is the wrong thing."

The claims of Mr Andy and four other artists are backed by five ­former studio staff who worked in the Adelaide studio.

One of them claims she regularly painted on the canvases of Indigenous artists and she was instructed to do so by the management. ​

However the board of the ­collective and Ms O'Meara ­vehemently deny the claims.

"My staff and I have a deep and ongoing respect for Tjukurpa," Ms O'Meara said.

"The APY Collective proudly supports culturally informing work. Respect for Tjukurpa informs everything we do."

In 2021-22 the APYACC made total sales of $3.8m and it says that $3m of this was returned to artists and arts centres on the APY Lands.

An independent review has been commissioned by the National Gallery of Australia for an upcoming exhibition of artworks from the Aṉangu Pitjantjatjara Yankunytjatjara Lands, often referred to as APY Lands, scheduled to run from 3 June to 8 October.