pure ftpd : how to set owner on files uploaded

I have a debian with pure ftpd installed with virtual users. I used the documentation for my setup so the local account of pure ftpd is ftpuser:ftpgroup When a user uploads a file, the file is owned by ftpuser:ftpgroup. I want the uploaded file to be owned by another system user (mylocaluser). I added my virtual user this way : pure-pw useradd uploadimages -u mylocaluser -d /var/www/mysite/current/images