You can use the ftp_put function if you want to FTP these files.
<?php
$file = 'somefile.txt';
$remote_file = 'readme.txt';
// set up basic connection
$conn_id = ftp_connect($ftp_server);
// login with username and password
$login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass);
// upload a file
if (ftp_put($conn_id, $remote_file, $file, FTP_ASCII)) {
echo "successfully uploaded $file\n";
} else {
echo "There was a problem while uploading $file\n";
}
// close the connection
ftp_close($conn_id);
?>
Source: PHP Manual available at link
As heavy files, consider using ajax in your requests and the set_time_limit
function on the server side.