allow or disallow comments by user role.

I administer a wordpress site for a non profit organization. It ios set up more as website than a blog. It’s purpose is to provide some Public Information as well as a communication tool by the organizations officers and committees.
What I would like is the ability to have a user role level that allows comments and levels that don’t. That way was certain committees could carry on a dialogue on their pages but others would not be able to comment.