Create FTP account remotely from web application

Hi to all, I have a web application from which I need to create some FTP accounts on another server. Between the servers I can have SSH, FTP or WEB(and some other if necessary but I don't think so) access but I don't know how to create the "relation" between the web scripts and account creation and of corse without to compromise the security of the systems. I need some advice. Thanks in advance. Andy.