Demand for the latest iPhone, which goes on sale on Friday, is so great many customers will not be able to get their hands on the gadget until October.
The phone, which is thinner and lighter than previous models and can use the newly-announced 4G network, will cost from £529 with the 32GB model selling for £599 and the 64GB version costing £699.
It goes on sale at 34 Apple stores from 8am.
The phone, which weighs in at 112g, has a 4in screen - half an inch bigger than previous models and has a new, more powerful A6 chip.
Its (Euronext: ALITS.NX - news) voice control software Siri, first unveiled in the iPhone 4S, has been updated so users can ask it to recommend films and restaurants and update their Facebook accounts verbally.
The battle for domination of the mobile and tablet market has become increasingly heated recently with Apple's competitors taking it on with a series of new products.
Nokia (Stockholm: NOKI-SEK.ST - news) and Microsoft (NasdaqGS: MSFT - news) recently joined forces to launch two new phones which will run on the Windows operating system and online retailer Amazon unveiled new models of its Kindle Fire tablets, which were previously not for sale in the UK, and are seen as rivals to Apple's best-selling iPad.