Apple’s as yet unconfirmed new edition of the iPhone is reportedly already in testing, mounting online speculation suggests.

According to a report from MacRumours, an iPhone app dubbed iBart that assists users in finding their way around San Francisco’s train network is being employed on a hitherto unseen model of the handset.

The developer of the app told the site that he has seen device signatures in usage analysis that read 3,1. The last 3G S version of the phone employed the identifier 2,1.

Further adding to the speculation is that the signatures apparently stem from the Cupertino area of San Francisco where Apple is headquartered.

Apple has yet to confirm whether it will be bringing a new mobile phone to market this year or how such a device would differ from previous iPhone incarnations.

However, were the tech giant to do so it is likely that it would appear worldwide in June, in keeping with launch dates for earlier editions of the handset.