Tech giant Apple is expected to unveil the latest version of its best-selling iPhone tonight.

The secretive company is hosting a “special event” which typically involves Apple executives unveiling new products to a specially invited audience.

The message included the line “it’s almost here” and also featured a figure 12 with a shadow that appears to be the number 5 – seemingly confirming the company will announce the arrival of the iPhone 5.

It comes a day after the UK’s largest mobile network operator unveiled plans to launch the country’s first superfast 4G products and services in time for Christmas.

Yerba Buena Center for Arts in San Francisco, where later today Apple is set to unveil the iPhone 5

Orange and T-Mobile owner Everything Everywhere, which was renamed today as EE, will make the state-of-the-art technology available to some 20 million people in 16 cities across the UK.

The 4G network – which offers speeds up to five times faster than 3G – will be available on HTC, Samsung, Nokia and Huawei devices, as well as “one more to come”, widely expected to be the Apple product.

The 4G services will allow uninterrupted access to the web on the go, high definition movies to be downloaded in minutes and TV to be streamed without buffering.

The battle for domination of the mobile market has become increasingly heated recently with Apple’s competitors taking it on with a series of new products.

Nokia and Microsoft recently joined forces to launch two new phones which will run on the Windows operating system.

The Nokia Lumia 920 and Nokia Lumia 820 are the Finnish company’s attempt to claw back lost ground since it lost its position as the world’s biggest phonemaker to Samsung.

Online retailer Amazon recently unveiled new models of its Kindle Fire tablets, and are seen as rivals to Apple’s best-selling iPad.

It is around a year since Apple unveiled the iPhone 4S complete with voice recognition software and an A5 chip allowing it to use much faster graphics for gameplay and to download data twice as fast.