(Reuters) – Apple Inc has started testing a new iPhone and the next version of its iOS software, news website The Next Web reported.

Apple shares were up 2.6 percent at $546.06 in premarket trading. The stock closed at $532.17 on the Nasdaq on Monday.

Application developers have found in their app usage logs references to a new iPhone identifier, iPhone 6.1, running iOS 7 operating system, the website reported.

Apple’s iPhone 5 bears the identifiers “iPhone 5.1″ and “iPhone 5.2″ and is powered by iOS 6 operating system.

Developer logs show that the app requests originate from an internet address on Apple’s Cupertino campus, suggesting that Apple engineers are testing compatibility for some of the popular apps, the website said.

“Although OS and device data can be faked, the unique IP footprint leading back to Apple’s Cupertino campus leads us to believe this is not one of those attempts,” the website said.

Apple launched iPhone 5 in September and it has been reported that the new iPhone will be released in the middle of 2013.