Disabling svn+ssh access?

Hi,

usually users access the repository via WebDAV, and that works really
fine. Some users, however, manage to checkout via svn+ssh (the users
have an account there and the right permissions to do so and I can't
easily change that), but this causes problems, as some hook scripts
don't run due to permission problems. Also users confuse passwords etc.

So I want to disable the svn+ssh access without disabling the ssh
access. How can this be done?

gruß,

-- 
Lutz Frommberger
SFB/TR 8 Spatial Cognition - Project R3-[Q-Shape]
Cognitive Systems Research Group, Universität Bremen
http://www.cosy.informatik.uni-bremen.de/staff/lutz/