STOCKHOLM, Sweden — Swedish online second-hand shop Sellpy, which is majority-owned by fashion giant H&M, has launched in Germany in a first step outside its home market as it bets on shoppers trending towards more sustainable consumption.

The start-up handles the entire sales process from picking up the goods from sellers' homes, to photographing, selling and shipping.

Sellpy announced in May that it would double its warehouse capacity in Sweden, to near eight million items annually, due to strong demand. Since Sellpy's foundation in 2014, more than six million items have been sold through the platform, it said.

The second-hand market is one of the fastest growing economic sectors within the fashion industry, Sellpy and H&M said in a joint statement on Monday.

H&M first invested in Sellpy in 2015 and now holds a 70 percent stake.

"We see that the awareness and demand from our customers for sustainable fashion is constantly growing and is now probably greater than ever," H&M Germany manager Thorsten Mindermann said.

"That's why we're particularly pleased to be able to offer a new sustainable way of buying and selling fashion, in collaboration with Sellpy," he added.

Seeking to improve its environmental credentials and tap into consumers’ growing concerns about the environmental cost of fast fashion, H&M has in recent years launched trials such as vintage clothes sales and party dress rental.

By Anna Ringstrom; editor: Ed Osmond.