Instagram is to begin trialling online shopping from within the photo-sharing app, the social media site has said.

Beginning in the US next week and involving an initial group of 20 retailers, posts to the Facebook-owned site from brands including Kate Spade and JackThreads will include tags for products shown in the photos, that if tapped will display price information and links to buy them.

Parent company Facebook introduced a marketplace to its mobile app last month as a way for users to buy and sell items from each other.

"Mobile has changed the way people shop," Instagram said in a blog post announcing the new feature.

"You browse products while waiting to be seated for dinner, make purchases on your commute into work, and compare prices online when you're at a store to see what's the better deal.

"While browsing and discovery is easy on mobile, finding more information about the specific products you see isn't always as simple.

"On a platform known for its power of mobile discovery, today we're excited to announce an easier experience to shop the products you love on Instagram."

Instagram said up to five products will be tagged per photo by participating retailers, with a "tap to view" icon appearing at the bottom of an image to alert users to the shopping information being available.

The social media site did not comment on when the feature will be extended to the UK, and the trial will initially only be used in Apple's iOS version of the Instagram app.