iQ Block Country is a WordPress plugin that enables you to block people from certain (obscure) countries that have no business visiting your blog and perhaps only leave spam comments or other harmful actions than this is the plugin for you.
You can choose which countries you want to ban from visiting your blog. Any visitors from that country get a HTTP/403 error with the standard message “Forbidden – Users from your country are not permitted to browse this site.” The message is customizable an can be styled with CSS.
If you only want to block other countries from visiting your backend (administrator) website then this plugin can do that.
This plugin uses the GeoLite database from Maxmind. It has a 99.5% accuracy so that is pretty good for a free database. If you need higher accuracy you can buy a license from MaxMind directly. If you cannot or do not want to download the GeoIP database from Maxmind you can use the GeoIP API website available on http://geoip.webence.nl/