Restricting issue visibility to different groups of users in one project

[Tomasz Lewandowski]

I have a use case where I have project (service-desk alike) where users representing different customers creates issues.
I want to limit visibility of issues  so the users representing one customer can only view issues related to that customer. Let's say I have approximately 50 customers and over 100 users representing them.

What is the best way to achieve that in JIRA? 

[Nic Brough -Adaptavist-]

It's a job for Issue Security