\copy command: how to define a tab character as the delimiter

Hi,

I tried to import a text file using the \copy command in psql using the following:

\copy foo (foo, bar) from foobar.txt delimiter as '\t' csv header

but that gives me an error:

ERROR:  COPY delimiter must be a single one-byte character

So how can I specify a tab character if I also need to specify that my file has a header line?

Regards
Thomas