Slingshot requires users to share something before they can view images from others."We are not a messaging app," said Joey Flynn, a product designer with the Slingshot project.

"The dynamic of requiring users to share something each time they want to see everything their friends have sent since they last used the app has the potential to encourage people to upload more often and to be more creative about what they share," Flynn was quoted saying in a report.

With Slingshot, photos and videos self-destruct after they are viewed. But recipients can look at a photo or watch a video on loop, for as long as they wish before flicking it away with their finger, the report added.

Facebook said for the new app, the list of friends is primarily built from phone numbers, culled from a smartphone's address book.