Could Apple's brief message herald arrival of iPhone 6?

Apple has released a cryptic invitation to an event at which it is expected to announce the latest incarnation of its popular smartphone - iPhone 6.

Apple's brief invitation raises more questions than it answers

Media outlets received a tantalisingly brief message consisting of a date, and the words "Wish we could say more".

Many experts are predicting that iPhone 6 will be the first to come in two different sizes - a 4.7 inch and 5.5 inch model - and that it will feature better connectivity to other smart appliances.

Apple may also choose the event, which is to take place at its headquarters in Cupertino, California, to unveil its long-awaited iWatch.