Updated below: Facebook has finally started taking action against its knockoff sites, and has first sued the one most easily accessible in terms of regulatory laws: it has filed a copyright lawsuit against StudiVZ, a German social network which looks very similar, and accuses it of “copying the look, feel, features and services” of the Facebook site, reports FT. The lawsuit was filed in a California court. It says that any differences between the two sites were “nominal” and accused StudiVZ of merely “replacing Facebook’s blue colour scheme with a red one”.

The German company that claims 10 million users and calls itself “the most successful social network in Germany, Austria and Switzerland”. Facebook launched a German version a few months ago, but has struggled to gain traction there, the story says. StudiVZ was bought out by Holtzbrinck group, the German publishing giant, for a reported $112 million late in 2006.

Meanwhile, at least 9 other Facebook clones have been documented before, and would be interesting to see if Facebook goes after at least some of them, most notably Xiaonei, the big Chinese social network which looks exactly like Facebook, except for the language part. Xiaonei is owned by the Chinese Internet holding firm Oak Pacific Interactive.

Updated: StudiVZ says the suit is without merit…it filed for declaratory judgment at the District Court in Stuttgart, also on Friday, when the Facebook suit was filed. StudiVZ claims Facebook is suing them only because Facebook hasn’t done that well in the German market. “Their strategy appears to be: ‘If you can’t beat them, sue them,”’ said Marcus Riecke, CEO of studiVZ. Not sure if they can completely deny the similarities, though…it is there for everyone to see.

• German Social Network StudiVZ Sold To Holtzbrinck For $112 Million
• Oak Buys China’s Facebook-Clone Xiaonei.com