Hi vijiglad, you can't directly copy from a server to a server without the file going through your server (not with PHP).
The solution is to split the procedure into two steps:
1] download to a temporary location on your server
2] upload to the target server and then delete the temporary file on your server
For help with using FTP in PHP have a look at examples for functions ftp_get() and ftp_put().
http://cz.php.net/manual/en/function.ftp-get.php
http://cz.php.net/manual/en/function.ftp-put.php
