Tens of thousands of letters mailed around the US could have picked up trace amounts of anthrax while passing through a contaminated postal centre, the nation’s top anthrax investigator has said.

A New York woman who mysteriously died of inhalation anthrax did handle the post at the hospital where she worked.

An investigation into how a New York hospital worker died from inhalation anthrax is being stepped up.

A 61 year old woman has died from inhiliation anthrax in the United States. Kathy Nguyen died three days after walking into the Lennox Hill Hospital in New York.