Australia Post has apologised for an "unacceptable" sign displayed at an Adelaide store.
The poorly worded notice, spotted at a post office in Adelaide's Rundle Mall, was meant to communicate that it could not take photos for Indian passports.
However, it read: We unfortunately CAN NOT take INDIAN photos".
In a smaller font above this sentence, it explains this is "due to our lighting and quality of photo background".
The sign was posted on a social media page, where it was met with hundreds of comments expressing disappointment over the wording.
An Australia Post spokesperson said the company "apologises unreservedly" for any offence caused by what has been described as an "unauthorised sign".
"As soon as we were made aware, we immediately removed the sign and have spoken with the team member concerned," the spokesperson said in a statement.
Australia Post was "fully investigating the issue" and "appropriate action" would be taken, the spokesperson said.
In a letter to Australia Post's CEO Paul Graham, Communications Minister Michelle Rowland said she was "deeply disturbed" by the sign.
"The message displayed in relation to passport photos was unacceptable and has caused great offence," she said in the letter, posted on Twitter.
"No one should be discriminated against because of the colour of their skin or where they are from."
She called on Mr Graham to explain what Australia Post would do to ensure an incident like this does not happen again.
Social media users speculated that India's passport photo requirements differ from Australia Post's service and could be the reason behind the store's sign.
"While the wording of this sign is inexcusable, we understand the Indian Consulate had rejected a number of customers’ passport photos provided by this Post Office," the Australia Post spokesperson said.
"We have reached out to the High Commission of India to understand the issue with the photographs, so we can rectify this urgently.
"Although no offence was intended, this lapse in judgement falls well below the standard we expect from Australia Post team members."