Prototypes of the third generation iPad are already in circulation among members of Apple's supply chain, it has been claimed.

However, analyst Mark Moskowitz of JP Morgan reckons that the iPad 3 won't be launched until the summer of next year, as Apple is in no hurry to launch the device. His comments, reported by Apple Insider, suggests that industry insiders think that the competition are so far behind the iPad that rushing out a third generation model would be premature.

"In our view, Apple should be in no rush. The other tablet entrants have stumbled so far, and that trend could persist deep into 2012," Moskowitz said.

Earlier this year, it was thought that Apple could be planning to launch the iPad 3 before Christmas and perhaps as early as this month. However, it was later claimed that shortages of key components would prevent a 2011 launch.

But it is thought that most of the components have been selected and certified, perhaps including a thinner, lighter battery and a higher resolution display, which will be similar to the iPhone 4's Retina display.

Moskowitz believes that the forthcoming Amazon tablet could be a realistic challenger to the iPad, but he thinks that Sony's recently-launched tablets will fail.

"To us, Sony's tablet lacks the refined, sleek feel of the iPad and its bezel-like back is not user-friendly. The sony tablet runs on the Android OS, which has failed to garner as much interest in tablets as it has in smartphones," he said.