maven-scm-plugin 1.9.4 - too old to work with working copy

Question

i am using 1.9.4 version of maven-scm-plugin,

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-scm-plugin</artifactId>
 <version>1.9.4</version>
</plugin>

and i am getting an error

svn: This client is too old to work with working copy 'E:\branches\project'; please get a newer Subversion client

1. how do i know what is the svn version that maven-scm-plugin support or use...?
2. What is the maven-scm-plugin version that support for svn 1.6...?