Mobile phone giant Apple is expected to announce its latest smartphone – the iPhone 5s – this week, following the news that invitations have been sent out for an event at its American HQ.  The emailed invitations feature the Apple logo surrounded by multi-coloured dots with the text: “This should brighten everyone’s day.”

The form of the invitation has further fuelled rumours that the latest generation iPhone will be available in colours other than the traditional black and white.  The event will take place on 10th September at Apple’s HQ in Cupertino, California.

Other potential features that have already been rumoured include a fingerprint sensor designed to help increase security levels and an improved camera of either 12 or 13 megapixels.

There have been rumours flying around that a second, cheaper version of the iPhone – the iPhone 5c – will also be released this year; it is therefore possible that it is this device and not the iPhone 5s that will be released with multiple colour options.

Analysts have claimed on several occasions that a cheaper phone could encourage growth for Apple in markets such as China and India, where budgets are lower.  Samsung is often cited as a good example of this approach.

Apple has already announced this year that it will be introducing an entirely new operating system – iOS 7. Chief executive Tim Cook has described iOS 7 as “the biggest change to iOS since the introduction of the iPhone.”