Mozilla technical evangelist Paul Rouget has criticised Internet Explorer 9 (IE9), the latest browser version from Microsoft.

Citing IE9’s compliance with website technical standards, Rouget wrote in a blog, "IE9 is definitely better than IE8 and a step in the right direction, but I don’t believe it to be a truly modern browser."

"The reality is that IE9 is two years late."

Rouget contested Microsoft’s claim that its new browser is 99% compliant with HTML5, the new Web language that supports video and interactive elements in modern Web pages.

Rouget said Microsoft’s figure was not based on industry standards but on in-house tests. Rouget also provided a list of Firefox technical features that are not present in IE9. It includes Web Workers, HTML5 forms, JavaScript Strict Mode and WebGL.

Microsoft is on record criticising the tests, caniuse and html5tests, that are used by Mozilla, arguing they do not test the depth of an implementation. Microsoft said that IE’s approach to HTML5 is optimised for real-world practices.

It said in a blog, "We spent much time researching and looking at what developers are building today and what they want to build tomorrow to define what we build in Internet Explorer 9 today."

Both Firefox 4 and IE9 are slated for an official release soon.