Copies of the latest version of Apple operating system have leaked onto the Net. Beta versions 10.5 of Mac OS X, also known as Leopard, are circulating on filesharing networks.

The software claims to be a copy of the beta software distributed to developers at last week's WWDC developer's conference event, and appeared over the weekend. Apple offered a peek at the OS at WWDC, and copies of the software were given to attendees so they could begin tweaking their software offerings for it.

Despite handing out copies, the company is likely to take a dim view of it being made widely available however. A similar leak last year prompted Apple to find and sue the developers responsible. Developers attending WWDC are made to sign strict legal agreements not to distribute software they receive.

Early responses from people claiming to use the software report that certain parts of it feel incomplete. Apple last week told the public that it intended keeping some features secret as Mac OS X heads for its showdown with Microsoft's Vista OS early next year.