US officials are investigating after the Pentagon mistakenly shipped live anthrax spores to government and commercial laboratories in as many as nine states, as well as one overseas.

A space capsule ferrying the first comet dust samples to Earth parachuted on to a remote stretch of desert before dawn today, drawing cheers from elated scientists.

The US Justice Department is preparing to give lie detector tests to hundreds of government workers at two centres where anthrax is stored, hoping to identify suspects in the letter attacks.