Thanks Maciej, The 5.3.1.Final/org.drools.updatesite-5.3.1.Final-assembly.zip you specified in the link doesn't have the issue. The version which I had issues were below. I am providing the links incase others run into the same issue with these versions.
http://download.jboss.org/drools/release/5.2.0.M1/drools-5.2.0.M1-eclipse-all.zip
http://community.jboss.org/servlet/JiveServlet/download/15922-6-25925/jbpm-5.0.0-eclipse-all.zip
thanks
lakshmi.