Kelly Thompson, who has worked for high-profile clients including Mimco, Sportsgirl and Maybelline NYC, said three drawings were taken from her website and used as prints on a skirt, dress and two long-sleeve tops.

The clothes have appeared for sale on at least two websites, including Choies and Sheinside, with price tags of up to $40.

"It makes me furious, especially because I work really hard to build a brand," Thompson said.

"If a client sees my work on a terrible product or website and they don't know I had nothing to do with it, I could lose a job. It's just a real pain I have to do this."

A Choies customer service operator said the clothes had been provided by a wholesaler, but refused to name which.

"I'm sorry we cannot tell you this," the operator said when contacted online.

"We are really sorry for the trouble and we don't mean to use others' design. If we did, we will show our regret for it and take some action immediately. Of course, we are trying to avoid the problem."

After Thompson contacted Choies, the garments were removed from its website, but a skirt still remains on sale on Sheinside's website.

It is unclear where the companies are based but they both offer postage around the world.

Thompson said she was now struggling to find the wholesaler in order to get compensation for the use of her imagery and to prevent her drawings from being distributed illegally around the world.

"I have no idea how many things are being made around the world with my images," she said.

"It's important that I publicly make a stand because I don't want people to think they can just rip my work off."

Fans have leapt to the support of Thompson. Some have called for a boycott of the websites selling the products and inundated the companies' Facebook pages with comments, while others have offered her legal help and services.

It's not the first time Thompson's images have been used without permission.

A Colombian company printed one of her illustrations on a T-shirt in 2010. After a legal battle, she received compensation and donated the remaining stock of T-shirts to a charity.

Australian Copyright Council executive director Fiona Phillips said the council frequently received inquiries from creators whose work had been used without permission.

"It's so much of a common issue that we actually even produced an information sheet about copyright and T-shirts," Phillips said.

"I think a lot of people think 'I like that image, let's make money out of it.' It's actually, unfortunately, a common issue and, obviously, once you're dealing with the internet you're dealing not just with stuff in Australia but potentially all over the world."

Jeremy Wortsman, the director of creative agency The Jacky Winter Group, said it was nearly impossible to receive compensation when smaller, overseas agencies used an artist's work without permission.

"It's, unfortunately, very common. It's a pretty big issue, it's happened to a few of our artists before," Wortsman said.

"It's the same as music and movies and anything else that is regularly pirated online. Images are proliferated in the same way - there's this feeling that you can take it, make commercial gain from it without having to pay for it."

It's not just smaller garment manufacturers that have felt the heat for stealing designs from independent artists.

Major fashion company Urban Outfitters has been accused of nicking artists' ideas and designs, as has chain Forever 21.