Using Grails 2.0.0, external jar files are not included in build path

After starting a new grails 2.0.0 project (not upgrading my old one) there seems to be no way for any external jars to be added to the project. I have added my jars on the build path (tried adding them as external jars, as native jars and as a part of a user defined library), placed them inside the lib folder and then tried refreshing dependencies. Despite all that, I keep getting compile time errors from missing imports, as it seems that the compiler does not know where to look for the imported packages.

I face the above issue with Grails v2.0.0 + Groovy v1.8.4 + sts 2.8.1 release.

Let me add that while using Grails v1.3.7 + Groovy v1.7.10 + sts 2.8.1, I faced no problems with imported jars whatsoever.