WASHINGTON (AP) – Cabinet secretaries participated in a drill Saturday that simulated a smallpox attack as the government tested plans to counter the potential use of bioweapons by terrorists.

“The purpose of this exercise, which was only a drill, was to address the federal government’s response to a potential smallpox attack,” said Dana Perino, a White House spokeswoman. “While there’s concern, we do not have any concern that a smallpox attack is imminent.”

The World Health Organization reported the disease was eradicated in 1980. Still, there are fears that smallpox could be used by terrorists as a biological weapon.

The United States ended routine childhood vaccination against smallpox in 1971. After the Sept. 11, 2001 terrorist attacks, however, the Bush administration ordered some military personnel vaccinated and recommended shots for front-line health care workers.

The government has stockpiled enough smallpox vaccine for everyone in the U.S., Perino said. It also has helped develop a new vaccine, which is in clinical trials, that does not appear to have the same potential negative side effects as the earlier one, she said.

In 2004, President Bush signed an order directing government agencies to help protect the country from an attack with biological agents.

A revised version had 59 instructions for agencies to improve the nation’s defenses, including improving the Biowatch system of sensors that continuously monitor and analyze the air in 31 cities.

Officials from various government agencies, including Centers of Disease Control Director Dr. Julie Gerberding, participated in the four-hour exercise to identify gaps in local and state preparedness plans and fine-tune the federal government’s response.

Members of the Cabinet who participated were: Homeland Security Secretary Michael Chertoff, Health and Human Services Secretary Mike Leavitt, Agriculture Secretary Mike Johanns, Transportation Secretary Norman Y. Mineta and Veterans Affairs Secretary Jim Nicholson.

Bush, who was spending the weekend at the Camp David presidential retreat in Maryland, did not take part in the drill, which was held in a conference room at the Eisenhower Executive Office Building next to the White House.

Saturday’s simulation was the second drill to check the nation’s readiness for catastrophic attacks. Federal officials said that a similar rehearsal in December for pandemic flu showed that saving lives and containing economic damage would require more planning in local communities and increased production of vaccines and medications.