Banning my UK website from Indian, Indonesian and Pakistan IP addresses

General information for the website: We run a web agency website in th Uk but get so much spam through our web forms and to our emails from people in these 3 countries who view our website and it totally ruins our analytics that we simply want to do ban visitors viewing our website.

I am thinking the best way to do this is to create a simple one page called bannedcountry.htm which will simply say "sorry we do not supply or use services from this country".

Description of requirements/features: We need htaccess or robots.txt written (up to you of the best way), to use an up to date list of all the country IPs available from India Pakistan and Indonesia and these 3 countries will only see the bannedcountry.htm page.

Finally, we would also like to update this IP list every so often in case new IPs get added to these countries, so would like advice or support on this every few months. Finally we want to make sure this code does NOT accidentally ban UK visitors but only for the 3 countries mentioned. This is very important as google rankings in the Uk is very important to us and we don't won't to ban wrong people.

Specific technologies required: Htaccess or robots.txt