Responding to a tip, TechRadar found that the term "iPhone 5 32GB" was posted on the Apple Accessories section of mobile giant O2's web store.
The much-rumoured new version of Apple's smartphone is often referred to as the iPhone 5, despite it actually being the sixth generation of the popular product.
In a statement issued to TechRadar, O2 confirmed that the mention was an error.
"The listing on the O2 shop is a genuine mistake and we are working on removing it from the website," said a spokesperson for the firm.
Pressed on whether the network was preparing for the iPhone 5's launch, the spokesperson added: "Absolutely not, it was just human error."
This would not be the first time that the as-yet-mythical iPhone 5 has been listed in error.
A web page for the Vodafone Sure Signal, a product which boosts the carrier's network signal, included a list of compatible phones in September 2011, including the mention of four types of iPhone 5.
However, the following month Apple surprised everyone by in fact just announcing the iPhone 4S, an update on 2010's iPhone 4 model.
Speculation is reaching fever pitch over the make-up of Apple's new smartphone model, including rumours that it will be announced by Apple at an event in the US on September 12.
Various reports have suggested that the new iPhone will come with a larger 4-inch screen and a slightly redesigned body, while new features are expected to include 4G, NFC technology and the iOS 6 mobile operating system.
Meanwhile, Apple is expecting to sell more than 250 million units of its next-generation smartphone after the product launches, according to calculations based on statements made by a senior Apple executive.