Apple Inc distributed invitations to an event in San Francisco on September 12, setting the stage for what is widely expected to be the release of its latest iPhone.

The invitation offers a clue that the fifth version of the popular iPhone could be in the pipeline. The invitation says "It's almost here." A large number 12 on the invite, corresponding to the date of the event, casts a shadow of a number 5.

The event will take place at San Francisco's Yerba Buena Center for the Arts, the site where Apple has unveiled various past products such as the iPad.

(Reporting By Alexei Oreskovic; Editing by Tim Dobbyn)