Using www and without www url both for same site

Using www and without www url both for same site

site url is lgagro.com.sg currently it redirect to
www[dot]lgagor[dot]com[dot]sg if opend without www. I want to access it
with and without www ie when i open it by http://lgagro[dot]com[dot]sg it
should work and if I open it using www[dot]lgagro[dot]com[dot]sg it should
also work without re-writing the url.
I have .htaccess file in root folder which is as such:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
the site url is set to http://www[dot]lgagro[dot]com.sg I also tried with
http://lgagro[dot]com[dot]sg
I have another site http://shashwatinternational[dot]com/ which works in
desired way. I don't have any other setting in shashwat. None of the site
are multisite. any suggestino will be helpful Thanks.