Yes, sorry - schoolboy error not to have posted the script code. So, amendments made to add the debug flag, the offending call is:

    # use the STEP param specified SFTP port
    printlog( "Opening an SFTP connection to $FTPaddress at port($SFTP
+PORT)");    
    $ftp = Net::SFTP::Foreign->new($FTPaddress,
                                   user     => $FTPuser,
                                   password => $FTPpasswd,
                                   port     => $SFTPPORT,
                                   debug    => $debug,
                                   more     => [qw(-v -o PreferredAuth
+entications=password)]
[download]

The output of the log is:

20120503 12:23:50 Step [50]: 
The old API for Net::SFTP::Foreign inherited from Net::SFTP is being o
+bsoleted. Use Net::SFTP::Foreign::Compat for a package offering a mos
+tly compatible API or upgrade to the development version of this pack
+age and use the new and much improved API. at ********.pl line 252
20120503 12:23:51 SFTP: Will attempt to send (0) files to customer(man
+age02.bds.tv) as user(proadmin),
20120503 12:23:51 SFTP: Opening an SFTP connection to ******** at port
+(22)
sftp: Sending SSH2_FXP_INIT
OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to ******** [*******] port 22.
debug1: Connection established.
debug1: identity file /home/probatch/.ssh/identity type -1
debug1: identity file /home/probatch/.ssh/id_rsa type 1
debug1: identity file /home/probatch/.ssh/id_dsa type 2
debug1: loaded 3 keys
debug1: Remote protocol version 2.0, remote software version OpenSSH_5
+.3
debug1: match: OpenSSH_5.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host '********' is known and matches the RSA host key.
debug1: Found key in /home/probatch/.ssh/known_hosts:33
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssa
+pi-with-mic,password
debug1: Next authentication method: password
debug1: read_passphrase: can't open /dev/tty: No such device or addres
+s
debug1: Authentications that can continue: publickey,gssapi-keyex,gssa
+pi-with-mic,password
Permission denied, please try again.
debug1: read_passphrase: can't open /dev/tty: No such device or addres
+s
debug1: Authentications that can continue: publickey,gssapi-keyex,gssa
+pi-with-mic,password
Permission denied, please try again.
debug1: read_passphrase: can't open /dev/tty: No such device or addres
+s
debug1: Authentications that can continue: publickey,gssapi-keyex,gssa
+pi-with-mic,password
debug1: No more authentication methods to try.
Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
reading from ssh pipe failed () at *****.pl line 252
20120503 12:23:51 Step [50] complete.
[download]

As you can see from the warning at the top - that is why i assumed that Net::SFTP::Foreign was being depricated

Whoa, you are using a version of Net::SFTP::Foreign on the 0.xx series that I stopped maintaining six years ago!!!

Just install a recent version of the module.

Dammit! looks like i must have a rogue module somewhere then. I've just done the following:

sudo perl -MCPAN -e 'install Net::SFTP::Foreign'
[sudo] password for purcedw1:
Reading '/root/.cpan/Metadata'
  Database was generated on Wed, 02 May 2012 04:58:03 GMT
Fetching with LWP:
ftp://ftp.mirror.anlx.net/CPAN/authors/01mailrc.txt.gz
Reading '/root/.cpan/sources/authors/01mailrc.txt.gz'
......................................................................
+......DONE
Fetching with LWP:
ftp://ftp.mirror.anlx.net/CPAN/modules/02packages.details.txt.gz
Reading '/root/.cpan/sources/modules/02packages.details.txt.gz'
  Database was generated on Thu, 03 May 2012 11:15:03 GMT
......................................................................
+......DONE
Fetching with LWP:
ftp://ftp.mirror.anlx.net/CPAN/modules/03modlist.data.gz
Reading '/root/.cpan/sources/modules/03modlist.data.gz'
......................................................................
+......DONE
Writing /root/.cpan/Metadata
Net::SFTP::Foreign is up to date (1.71).
[download]

Thanks for the prompt reply - i shall confirm in due course :)