Worldwide alert on anthrax

America's State Department issued a new worldwide anthrax alert today as the number of people and places infected appeared to be spiralling out of control.

The warning follows the discovery of new traces of anthrax in an office building used by the US Senate in Washington.

The spores were found in a lift used to carry post inside the building, which houses the offices of Senate majority leader Tom Daschle, who was sent an anthraxcontaminated letter more than a week ago.

The discovery dashed hopes among investigators that they had tracked down all the sources of the contamination, which has shut down much of Capitol Hill and left even the White House without postal deliveries.

A second case of the less dangerous cutaneous anthrax has also been confirmed in a postroom worker at the New York Post newspaper.

Six US postal service employees from the Brentwood centre, near Washington - the same facility which employed two people who died of anthrax earlier this week - are being treated for suspected anthrax. Last night it was also announced that a woman congressional reporter is also in hospital after testing positive for anthrax.

Efforts to narrow down the source appear to be succeeding. It is now known that the anthrax found in Mr Daschle's office had been treated with a sophisticated chemical additive designed to make the spores suspend in the air. Only three countries, the United States, Iraq and the former Soviet Union, are known to have developed the additives.