.htaccess for .php extensions

Hee guys,

Im running into a little issue with 404 – not found pages. Somehow these redirects are generated by WordPress itself and not by the default .htaccess document in the root of my server.

Current status of 404 pages;

http://www.fietsverhuur-terschelling.nl/flower Works
http://www.fietsverhuur-terschelling.nl/flower.html Works
http://www.fietsverhuur-terschelling.nl/flower Works
http://www.fietsverhuur-terschelling.nl/flower.php Doesn’t work

The reason i want to get this fixed is that the old website had a lot of php pages in it, google still has some external links from the old site i would like to see redirected.

Can i fix this to add a redirect in the .htaccess file?

Current .htaccess file (standard)

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteRule ^back_office/?$ /wp-login.php [QSA,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>