Screenshots claiming to show the new Windows 10 Start menu have been leaked online it is claimed.
The hype appears to be growing over the new operating system, as the firm looks to bounce back from the underwhelming reception to Windows 8, which has struggled to match the market share of previous versions.
The images, which look very similar to those officially released by Microsoft at BUILD in April, have not yet been confirmed as authentic.
However, a source close to the company has told Neo Win that the "image appears to be legitimate." The pictures still contain Windows 8.1 branding, but this is said to be standard practice for internal builds and the new desktop won't be available until Windows 10 arrives.
Those who are sceptical over the leak point to the fact that the new images show a build date of 4 July, when no one was working at Microsoft due to the US Independence Day.
The photographs reveal a Windows 7 style Start menu accompanied by a more modern user interface column of tiles, matching what was shown at BUILD.
Read more: What Microsoft must introduce with Windows 9
Windows 10 'Threshold' is expected to launch in April 2015 with a public preview arriving in autumn this year. The new operating system may be released as a free update for both Windows 8.1 and Windows 7 SP1 users.