Limiting User Access to a Supplier or Category of Suppliers

I am wondering how we can limit access by user/group to specific suppliers.

As an example, a supplier, who happens to be an employee or some other ‘confidential’ supplier, is not able to be viewed by anyone who is not in an ‘accounting group’ but may still have access to other suppliers as their user group/role permits?

Some ideas-

* Is it possible to exclude Supplier group(s) from certain users
* Can we use the Category field?