O2 has been quick to dismiss reports that appeared this morning, which suggested that the mobile phone giant had totally run out of 8GB and 16GB iPhones.

It turns out that O2's online store was out of stock temporarily - and that supplies of the 16GB version currently being replenished. An O2 spokesperson also told TechRadar that there was no shortage of 16GB iPhones in its stores, but that the 8GB model was 'under review'.

Speculation that O2 was permanently out of stock of current 8GB and 16GB models is rife - especially since 3G versions of the iPhone are expected to be announced within the next few weeks.

3G iPhone launch

Reports yesterday suggested that AT&T Wireless employees in the US had had all vacation leave cancelled between Sunday 15 June and Tuesday 15 July. That fits in with expected on-sale dates for the 3G iPhone, which will most likely be announced on Monday 9 June - the date of CEO Steve Jobs' keynote speech at Apple's 2008 World Wide Developer Conference.

We still believe that the UK version of the 3G iPhone won't be announced here until September, with a possible on-sale date as late as November. These timings make the most sense, since they will enable Apple to satisfy demand in the US initially, while ramping up production for its international customers - don't forget 10 more countries in addition to the UK, France and Germany have also been told that they're to get it later this year, as well as Latin America.

The September and November dates are also less likely to draw the ire of O2 customers who have already signed up to its iPhone tariffs. Although there's nothing to stop you upgrading from an 8G iPhone to a 16GB version (provided you pony up £329 for the news handset). However it's not clear whether that would also apply to a 3G version of the iPhone, since tariffs for the new models are likely be different.

That's because the 'unlimited data' tariff offered by O2 is inevitably hampered by the use of a relatively slow 2.5G EDGE connection. A high-speed 3G iPhone is likely to encourage iPhone users to download more data - and there are likely to be some cost implications for that.