[TYPO3] Error deleting files in fileadmin folder

[Gunnar Jonsson]

I have a TYPO3 website running for a long time. Suddenly, I do not manage to 
delete files in the fileadmin folder. Everything else seems to work OK, like 
uploading and renaming of files. But when I try to "delete" one file I get 
the following error message:

Forbidden
You don't have permission to access /typo3/tce_file.php on this server.

I have tried to set full permission for all users, both on the file I tried 
to delete and the typo3/tce_file.php file. But nothing helps, I still get 
the permission error even if I set read, write and execute permission for 
all users on these two files.

Anyone who has some hints what is causing this permission error?

Regards,
Gunnar Jonsson