Counterfeit goods remain a big problem for global retailers, especially in Asia, the chief executive officer of Adidas told CNBC Thursday.

The German brand has calculated that up to 10 percent of the Adidas-branded products on sale in Asia could be fake. This includes products in stores and online.

“In Asia it is a problem, but that’s an overall market problem, where we believe that approximately up to 10 percent in certain categories are fakes, are copying … and we are seeing that in bricks and mortar and we are seeing that online,” Kasper Rorsted, chief executive officer of Adidas, told CNBC’s “Squawk Box Europe.”

“It continues to be a big problem for our industry,” he said.

The brand reported Thursday an increase in net profit during the first quarter of the year. This was driven by sales in North America, Greater China and online. Growth in Greater China alone was 26 percent in the first three months of the year.

Despite Adidas’ strong presence in the Chinese market, its chief executive is not worried about a potential trade war between Beijing and the United States. Rorsted said: “Most of our manufacturing in China is serving the Chinese market. The vast majority of the manufacturing that is serving America or Europe (is) situated in Indonesia and Vietnam”

Adidas confirmed Thursday its outlook for the year — an increase in sales of around 10 percent on a currency-neutral basis, driven by growth in North America and Asia-Pacific.

One of the most recent trends supporting the sales of sportswear is athleisure: a fashion trend where workout clothing is worn at casual and social events. According to Rorsted, this trend is here to stay.

“I think the trend towards more casualwear is only starting right now. So the question is not whether … the trend is going to continue, it is how you service that trend,” he said.