Macworld has received reports of frustrated customers being unable to pre-order the iPhone 4S through Apple's website this morning.

Pre-orders for the iPhone 4S opened this morning and UK customers can opt for a SIM-free model from Apple, or choose contract-only deals from Vodafone, T-Mobile and Orange. O2 and Three will be stocking the iPhone 4S but have yet to announce pricing or open pre-ordering systems.

iPhone 4S pre-orders open in UK

But one frustrated customer reported problems with webpages not loading on Apple's site, having tried for several hours to order an iPhone 4S.

The customer was eventually able to pre-order an iPhone 4S by calling Apple on 0800 048 0408.

Apple Insider reports that there was an initial hiccup with the pre-ordering process, with Apple's online store going back online later than initially promised. Cnet carries a similar report.

Apple has not yet responded to a request for comment. We've not been able to replicate the problems, but if you've been similarly affected please let us know in the Comments section below.