Twitter, the micro blogging website where users post in 140 characters or less is to start trials with a new buy now button for a small percentage of users in America.

Up to now it’s been possible to buy using a twitter hashtag but this has been very confusing for most users but now the buy button will be visible alongside messages offering particular services or products from specially selected retailers.

Nineteen companies have agreed to test out the new system including popstar Rihanna and fashion brand Burberry.

Time Limited items are the first to be sold such as tickets for concerts or limited edition merchandise says Twitter’s ecommerce boss Nathan Hubbard in the New York Times.