"I think it's quite disrespectful for people to make profit out of something like Anzac Day and remembrance.
"It's not a good look at all."
He said this was not the first time the patent had been used for commercial reasons.
"Anzac and Armistice Day, and times like that, they're the times that we stand still and remember people who served our country - the ones who didn't come back and the ones who were injured.
"So I don't think it's on for international companies to think it's okay to use New Zealand to make a bit of profit."
Upon seeing a photograph of one of the shirts by Redbubble, Mr Hill noted the soldiers in the image were wearing American helmets - not ones worn by New Zealand or Australian troops. "Even the weapons they're carrying are American weapons," he said. The use of the word "Anzac" on products breaches a law protecting flags, emblems and names.
A spokesperson of the Ministry for Culture and Heritage said the T-shirts did not breach the Act, as they were not made by New Zealand manufacturers or suppliers, meaning New Zealand had no jurisdiction over their trading.
Mr Hill said that was "a pretty weak stance" for the ministry to take. "Surely they have some way to protect the patent."
RSA national president BJ Clark said he was "concerned about [the] tastelessness" of using inferior products to commemorate those who served in war.
"Most people who want to create something to remember Anzac do it with good intentions but it's not so good if it's done directly for profit-making and there's a large company making a fortune out of it."
He said the RSA preferred to work alongside people who had ideas for commemoration. "That way some of the profits go back to the veterans."
The Herald's attempts to contact Redbubble and Tee Parks for comment was unsuccessful.
A copyright statement on Redbubble's site warns artists to make sure the work they upload is their own original ideas and is not infringing on intellectual property. "Certain works may be taken down without a specific report being received if we are otherwise alerted or aware of potential infringement issues", the statement says.