TWO US postal workers are feared to have died from the most deadly strain of anthrax.

Post-mortem examinations are being carried out today on the two Washington postal staff amid fears they contracted the inhaled form of anthrax.

Both men worked at the same central sorting office which handled a contaminated letter sent to Senator Tom Daschle.

Two of their colleagues are fighting for their lives after contracting the same strain of anthrax.

A further nine staff have reported flu-like symptoms which could be the early stages of the disease.

British-born Florida journalist Bob Stevens, 63, died on October 5 in the only confirmed case of inhalation anthrax.

America's postmaster-general John Potter said: "Our hearts are heavy knowing that two co-workers have become the latest victims of terrorism.

"Even though we have not received confirmation...we will proceed as though anthrax was involved."

The United States Post Office has pledged to spent a billion dollars on security measures, including machines which bombard letters and packages with radiation.

It is unclear who is sending the anthrax letters, which have targeted TV and newspaper newsrooms and politicians.

There is speculation the packages were sent by foreign terrorists, while others believe a deranged American acting alone is to blame.