Debian adds security support for amd64 (page 122)
More...Reported on: 2005-08-11
In chapter 4. Debian releases and archives on page 122:
Even though amd64 is not (yet) an official architecture, the Debian security team has declared that it will support the sarge release of the Debian AMD64 port, which was released shortly after the official sarge release.
Discussion
To receive security upgrades for an AMD64 system, add the following line to your /etc/apt/sources.list file:
deb http://security.debian.org stable/updates main
then run
# aptitude update # aptitude upgrade
on a regular basis.