No plugin found for prefix 'sonar' in the current project and in the plugin groups Error

No plugin found for prefix 'sonar' in the current project and in the
plugin groups Error

Everything was working fine till yesterday with Jenkins and Sonar (using
Maven). Suddenly I saw below error in Jenkins logs and build fails for all
projects with the same error.
[ERROR] No plugin found for prefix 'sonar' in the current project and in
the plugin groups [org.apache.maven.plugins, org.codehaus.mojo] available
from the repositories [local (/user/mysystem/.m2/repository), nexus
(http://localhost:8081/nexus/content/groups/public)]
I have sonar running and sonar plugin installed in Jenkins.
What could be the issue. Can any one help me on this regard.