php - How to set upload_max_filesize in .htaccess?

I have try to put theese 2 lines

php_value post_max_size 30M
php_value upload_max_filesize 30M

in my root .htaccess file but that brings me "internal server error" message ...
php5 is running on the server
I don't have access to php.ini so i think htaccess is my only chance.
Can you tell me where is the mistake?
Thanks in advance

Answer

php_value upload_max_filesize 30M is correct.

You will have to contact your hosters -- some don't allow you to change values in php.ini