An Aboriginal man has shared a photo of a threatening letter found in his letterbox in Adelaide, which refers to him in racist language and demands he "go back to the bush".

Key points: The man says his partner found the letter in their letterbox on Wednesday

The man says his partner found the letter in their letterbox on Wednesday He said he called police but was told there was nothing they could do

He said he called police but was told there was nothing they could do SA's Commissioner for Equal Opportunity said the letter made her "sick to her stomach"

Michael — who did not want his full name published — told the ABC the letter was found in his letterbox by his partner on Wednesday morning.

He said he had lived at the house in Taperoo, in Adelaide's north-west, with his partner and three kids for about seven years.

He said he believed someone in the neighbourhood was responsible and described it as "threatening" and "racist".

Michael said he believed the letter stemmed from an incident last weekend where police were called to his house.

He said his teenage daughter had been "mobbed" by a group of girls, so he called police to report it.

When police arrived, the girls that allegedly mobbed his daughter were also there and caused a "commotion".

"It was loud, and we had police everywhere," he said.

"I've apologised to my neighbours about what's happened and my [partner] has come home this morning from shopping and found that letter in the letterbox."

Michael said he also called police after reading the letter, but said he was told "basically nothing can be done about it".

'People can still be so narrow-minded'

He then decided to send a photo of the letter to a South Australian social media page, in a bid to raise awareness about racism.

"I honestly don't understand what their problem is because I'm one of the quieter people in the street," he said.

"I was stunned to think in this day and age you can still send a letter like that. That's like KKK tactics.

"I feel like the next thing they're going to do it burn crosses in my front yard or something."

He said he would have been happy to have spoken with the person about their concerns instead of reading the letter.

"I don't understand how people can still be so narrow-minded and have the audacity to walk to my mailbox and drop a letter and not knock on my door and speak to me," he said.

Many users on social media also commented in support of the family after seeing the letter published online.

"How disgusting is that, we are all equal," one user wrote.

"Geez, I bet they didn't give their name. Racist much," another user wrote.

The law 'doesn't cover this sort of thing'

South Australia's Commissioner for Equal Opportunity Niki Vincent told ABC Radio Adelaide that the note made her "sick" to her stomach.

"It just makes me feel helpless when I hear that and my heart goes out to that family," she said.

Dr Niki Vincent said the note made her "sick" to her stomach. ( Twitter )

"Many Aboriginal people tell me that they experience racism on a daily basis in small ways."

Dr Vincent said other than reporting the letter to police, there was not much else that could be done in a legal sense.

"I don't think our laws really cover this sort of thing well enough in South Australia, but even if there was better coverage we would have to know who sent this letter," she said.

She said the Racial Vilification Act and the Equal Opportunity Act only covered acts of racism in public places and employment.

"I am at a loss as well, I have an Act, I administer the law and it doesn't cover this sort of thing," Dr Vincent said.

"I feel like we really have to do more than just rely on the law to deal with racism."