Protecting /wp-admin and wp-login.php

I wish to protect the login to a set of restricted IP addreses. I attempted to do this, but seem to get redirect loops in certain situations.

Perhaps its conflicting with a WordPress security plugin to rename /wp-login.php to /login etc.

location ~ ^/(wp-admin|wp-login.php) {
allow 1.2.3.4;
deny all;
}

Could you include a set of rules for restricting the admin sections?

Thanks,

A