It has been revealed that the O2 website was handling 13,000 orders per second at peak times yesterday as the iPhone 3G went live for pre-order - and that the operator does not have as much stock of the new devices as it would like.

The company has come under much criticism from both customers and press for the technical difficulties that were experienced as the iPhone 3G area of the site went live - difficulties later described by O2 as due to "unprecedented demand".

This new statistical information has come to light thanks to a MacRumours reader having pasted the text from a letter he received from Stephen Shurrock, sales director at O2, in response to a letter of complaint he sent to the company's CEO over the chaotic iPhone 3G ordering process, in the site's forum.

Shurrock says: "The massive simultaneous crush, partly created by our open and honest communications approach with the registered community, exceeded even our worst case assumptions. Demand was at 13,000 orders per second. Frankly, we have to admit we just weren't prepared for this unprecedented level of demand. No website is".

He also warns things may be just as difficult in brick and mortar stores on Friday: "The approach on Friday will also be on a first come first served basis. The amount of devices will vary depending on the store but will be on average a few dozen iPhones in each O2 or CPW store".

Explaining the reason behind the discrepancy between demand and supply, the O2 executive appears to offer a candid insight into the pre-order process:

"We used the registration data to keep Apple up to date on the phenomenal interest and to support our orders for the phones with them."

"We have been working continuously with them to get as much stock for the UK as possible. Unfortunately, they have only been able to supply a small proportion of the number of phones we asked for, because they are launching simultaneously in 22 countries."

"We are confident that over time we will start to get sufficient volume to meet demand, but it is likely that stock will be in very short supply for some weeks to come."

According to Hitwise, the website monitoring service: "During the June peak, 22.4% of people searching for iPhone went to Apple’s official iPhone site, while 14.0% went to www.o2.co.uk. This time, O2 has taken the top spot, with 23.5% of traffic, compared with Apple’s 18.7%. That said, consumers still need a bit of nudge: 90% of O2's traffic from the term 'iphone' comes from paid search, up from 50% last month".