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Apple has released the latest version of its Mac operating system.

OS X Mountain Lion makes it easier to share material to social networks and also introduces a notification panel similar to that found on many smartphones.

The news was revealed in the company's <link> <caption>third quarter earnings release</caption> <url href="http://www.apple.com/pr/library/2012/07/24Apple-Reports-Third-Quarter-Results.html" platform="highweb"/> </link> .

Mac sales were 2% up on the year, but the results fell short of many analysts' forecasts.

The firm's shares dropped about 5% in after hours trading on Wall Street.

Users trying to download the new software sometimes received error messages in the hours after its release.

These included owners of new Macs who had been given coupons to redeem "free" copies of the system, but were told "this code has already been used" when they tried to use them.

Apple first announced the latest update to its operating system in February. The update continues a trend to introduce features to its desktop and laptop families that have already been implemented on its iPad and iPhone mobile devices.

These include the ability to upload and synchronise material with its iCloud internet storage service; the introduction of the iMessage service allowing text message-like chats between the firm's computers and handsets; the ability to easily share material to Twitter; and an application to compare the user's video game scores against those of their friends.

The firm has also taken steps to aid its expansion in China including the adoption of Baidu as a search service built into its web browser's toolbar, and buttons to make it easy to share material to the Sina Weibo microblog, and the video sites Youku and Tudou.

However, the firm's decision to keep its Mac system distinct from iOS for mobile devices is set to be challenged by October's Windows 8 release by Microsoft.

Microsoft is offering users the chance to run the same system on both their tablets and desktop computers, making it easier to share software between them.

Windows 8 - and its touchscreen Metro apps - have been described by Microsoft as the biggest revision to its interface in over a decade. But one analyst said Mountain Lion was more of an incremental step forward.

"While there are a lots of new features this is not a major upgrade like the last version Lion was," said Brian Blau, research director at tech research firm Gartner.

"But Apple has also been improving its Office-like software and creation applications along the way, so maybe it didn't need such a big revision. And you have to bear in mind it is only charging $20 [£13.99 in UK] for the change."

By contrast Microsoft is charging $39.99 for a Windows 8 upgrade, while Linux-based systems, such as Ubuntu and Debian, can be downloaded for free.