I have a site which has a default url say "http://www.blahblah.com/" (which is default in english language). In my site there is support for multi languages. I am having few links at my home page say "English" "French" "Spanish" etc. and on clicking these links user is redirected to these links:

http://www.blahblah.com/en-us/ (English)

http://www.blahblah.com/fr-ca/ (French)

http://www.blahblah.com/spanish-culture/ (Spanish)

and based on culture in the url I am showing the content accordingly to end users in their desired language. Now, this was how my site is. The issue I am getting is with SEO. I noticed Google is considering (I checked via Google web masters) my site pages as duplicate like:

1. http://www.blahblah.com/documents/ and http://www.blahblah.com/en-us/documents/

2. http://www.blahblah.com/news/ and http://www.blahblah.com/en-us/news

and similarly all the pages are considered as a duplicate content in Google webmasters tools. I am worried of this, since I think my site is getting penalized in ranking because of this. Could you drop some idea how to overcome this situation?