American Express has launched a purchase-by-tweet service for shoppers in the US.

American Express has launched a purchase-by-tweet service for shoppers in the US.

Its credit card holders post a specific hashtag on Twitter which triggers payments from their accounts.

The service offers products from Amazon, Sony and Microsoft at a discount to encourage customers to try it out.

Customers must link their card to their Twitter account via American Express’ app. They then need to go to the firm’s Twitter page and select the Favourites section to view items on sale.

American Express has tried out previous social media experiments. It operates a voucher-free discount scheme with Foursquare – a location-based network – in the UK and US.

It also previously offered savings to users who tweeted promoted hashtags.

American Express senior vice president for digital partnerships, Leslie Berland, told the BBC that the success of the firm’s existing social media schemes suggested that there was “significant power in combining our assets with Twitter’s platform”.