This worked great! Many thanks.

I have only a few remarks:

i) To be able to use sftp and scp, I had to add "/usr/bin/sftp /usr/bin/scp" to the APPS variable on the chroot env build script AND I had to copy /usr/lib/sftp-server to the chroot environment;

ii) I've also add "/bin/rmdir" to the APPS var. But this is only an option.