A prototype of an unreleased iPhone has been lost in a bar by a member of Apple's staff, it has been revealed.

According to a report by CNET, the incident - which echoes one last year when a prototype iPhone 4 was acquired by Gizmodo after being found in a bar in California, close to Apple's headquarters - saw the handset left at a "Tequilla Lounge" known as Cava 22 in San Francisco in July this year.

An unnamed source cited in the report says Apple contacted San Francisco police over the loss, saying the device was priceless, however Apple chose not to file a report about the loss.

The tech giant then went on to electronically trace the iPhone, which was discovered at an address in the Bernal Heights area of San Francisco. The owner of the home admitted being at the bar on the night in question but denied all knowledge of the handset, even when offered money for the phone with "no questions asked". Meanwhile, a search of the property failed to result in the lost iPhone. The report also speculates the handset may have been sold via online auction site Craigslist.

Last year's iPhone 4 incident resulted in a police investigation after Gizmodo published details on the handset on its website. The home of editor Jason Chen was even raided. Despite this, no charge was brought against the company after the District Attorney looking after the case revealed a crime has not been committed by the Gizmodo. However, Brian Hogan, who found the phone and subsequently sold it to Gizmodo for £5,000 after attempting to return the handset to its owner, Apple engineer Gray Powell, and his friend Sage Wallower, who helped with the Gizmodo transaction, were charged with misappropriation of lost property.

Although Apple has yet to confirm it will release another iteration of the popular smartphone, there has been much speculation that a new handset, dubbed the iPhone 5, will be released later this year.

No details about the look of the handset, the specifications or the OS its running have been leaked as a result of the loss.

Apple has declined to comment on the matter.