The FBI says that it is not linking a case of skin anthrax affecting an NBC employee in New York with the 11 September attacks. The US broadcaster reported that the employee works at Rockefeller Centre in Manhattan.
Skin anthrax is a different form of the disease to the one still being investigated at newspaper offices in Florida. One person died, and two more were infected in the Florida outbreak. NBC said the woman was not in danger.
As fears grow over other possible anthrax infections, the newsroom of the New York Times was evacuated for several hours today after a powdery white substance was sent to one of the newspaper's reporters.
US stocks fell as the market reacted to today's anthrax scares. Wall Street's blue-chip Dow Jones industrials index slumped 215 points at one stage and was down 68.92 points at close of trading.
The FBI earlier warned that there could be further terrorist attacks on American soil or against US interests abroad in the coming days. The warning was contained in a terse two-sentence statement.
"Certain information, while not specific as to target, gives the government reason to believe that there may be additional terrorist attacks within the United States and against US interests overseas over the next several days.
"The FBI has again alerted all local law enforcement to be on the highest alert and we call on all people to immediately notify the FBI and local law enforcement of any unusual or suspicious activity," it said.
During his first real press conference since 11 September, President Bush said that the FBI warning was the result of a general threat against America.
He said that it was important for American people to know that the country was on full alert. He urged Americans to report anything suspicious to the law enforcement authorities.
On military action in Afghanistan, he said terrorist training camps had been damaged, Taliban communications had been disrupted, its military weakened and most of its air defences destroyed.
He said $24m of Al-Qaeda money had been frozen. Asked how long would the action in Afghanistan last, he said as long as it took to root out the al Qaeda network and bring it to justice.
He said he did not know if Osama bin Laden was dead or alive. President Bush also Afghanistan's ruling Taliban a second chance to turn over terror suspect, Osama bin Laden.
President Bush said the action would be limited to Afghanistan for now, but he described Iraqi leader Saddam Hussein as an evil man. He asked every child in America to send a dollar to the White House to help bring relief to the children of Afghanistan.
