OpenSSH SCP question

How do you use scp to transfer a file between two remote machines that 
both use a non-standard SSH port? The -P parameter seems to only affect 
the second ("remote") host. So using a line like:

scp -P 99 oracle@xxxxxxxx:/home/oracle/backup.sh  
oracle@xxxxxxx:/home/oracle


doesn't seem to work when both machines are running ssh on port  99. 
Port number and host names changed to protect the innocent.

Any ideas?

thanks,
Sean

spkane@xxxxxxxxxxxxxx