Using the <!–more–> tag to require logins to read full post

I’ve been looking through the available plugins, and I am unable to find any resources to attempt to make the following:

I’d like a plugin that requires the visitor to log in to “read more” (i.e., anything after the <!–more–> tag).

Are there any plugins like this, or any suggestions on which checks should be in place to allow subscribers and admins to view the post’s full text? Note, this is not using the common [hidethis]registered content here[/hidethis] format, I’d like to use the <!–more–> tag to force all text below <!–more–> to require Subscriber access.

Many thanks!