The United States has done too little to prepare for another potential domestic anthrax attack six years after spore-laden mail killed five people, a former CIA director and other experts tell Reuters.

"I think we're very poorly prepared," James Woolsey, who headed the CIA from 1993 to 1995, said at a news conference to unveil a report by a security consulting firm warning of U.S. vulnerability to another anthrax attack.

Anthrax is a sometimes fatal disease caused by Bacillus anthracis, a bacterium that forms spores. The spores can be used as a biological weapon and are most deadly when inhaled into the lungs. Experts have worried particularly about the possible release of an anthrax weapon in an urban setting.

"Biological weapons have the potential lethality, if cleverly used, up in the range of hundreds of thousands of people and the range of millions -- up in the range of nuclear weapons -- but with relative simplicity of construction," Woolsey said.

"One is talking about assembling and operating something not much more complicated than a microbrewery attached to a restaurant," Woolsey said.

In the weeks after the Sept. 11 attacks, five people died and 17 others were sickened when anthrax spores were mailed in letters to media and government offices in New York, Washington and Florida. Those cases have not been solved.

The report released by ExecutiveAction, a Washington-based risk management and security consulting company, concluded that the United States faces a high threat of an anthrax attack and remains largely unprepared.

Reuters reports that ExecutiveAction CEO Neil Livingstone, an expert on terrorism, said the United States needs to do more to develop an improved anthrax vaccine, better drugs to treat people exposed to the spores and better ways to detect them.

Veronica Nur Valdes, a Department of Homeland Security spokeswoman, says the department is "very engaged" in efforts to strength preparedness for any anthrax attack.

"I think it's important to note that there's no credible information at this time telling us of an imminent threat to the Homeland, to include an attack involving anthrax," Valdes said. "But we're mindful as we build up our defenses and readiness that the bad guys will look for new ways to strike."

ExecutiveAction said it was hired by Maryland biodefense company PharmAthene Inc. to produce the report.

PharmAthene President and Chief Executive Officer David Wright said his company has a $13.9 million government contract to develop a new drug to treat inhalation anthrax.

The report illustrated the threat by laying out three scenarios involving an anthrax attack: spreading spores on New York's subway system, killing thousands; dispersing a smaller amount of the spores in a Minneapolis movie theater, Las Vegas casino and California theme park, killing hundreds; and an attack at the Academy Awards ceremony, killing famous actors.

"Congress needs to get much more involved right now. The administration needs to put this on the front burner," Livingstone said.

There is a vaccine to prevent anthrax but it is not available to the public. The U.S. military gives it to troops serving in Iraq, Afghanistan and South Korea.

Last December, the government ended an $877.5 million deal with VaxGen Inc. to provide millions of doses of anthrax vaccine because regulators refused to approve new tests of the experimental product. The contract had been aimed to stockpile enough doses to inoculate 25 million Americans, Reuters reports.