The U.S. Postal Service took steps to protect employees at Washington's central mail processing plant and other facilities during the October 2001 anthrax attacks, but postal officials need to clarify their guidelines for responding to any future contamination, according to a congressional report released yesterday.

Letters containing anthrax spores killed five people, including two Washington postal workers, and sickened 17 others in fall 2001. Postal employees have long questioned whether managers and administrators acted quickly enough to protect them.

The Government Accountability Office review found that the Postal Service kept the District's plant on Brentwood Road NE and four other buildings across the country open after handling contaminated letters because public health agencies advised them that the health risks to employees were minimal.

"Because public health officials underestimated the health risks involved, actions to protect postal employees were delayed," the report said.

The study criticized the accuracy and timeliness of the information that postal officials provided to workers in the immediate aftermath of the incidents. The problems stemmed from the uncertainty of the health risks and from a Postal Service delay in releasing anthrax spore counts in one instance.

The report also found that the Postal Service's anthrax response guidelines left unanswered several questions about how specific incidents would be handled in the future.

Postal officials "need to clarify the actions they'd take under certain kinds of scenarios," said Mark L. Goldstein, the GAO's director of physical infrastructure issues, who oversaw the report. "What would they do when they get preliminary evidence of anthrax contamination? Or if a postal employee is diagnosed with anthrax? They still haven't clarified some of that guidance."

Henry A. Pankey, the Postal Service's vice president of emergency preparedness, acknowledged in a letter included in the report that "we would have made some different decisions had the present state of medical and scientific knowledge been available to us in October of 2001."

Pankey also wrote that the Postal Service has made -- or is making -- revisions to its guidelines.

The government watchdog group Judicial Watch sued postal officials last year, alleging that they kept the Brentwood Road plant open for at least four days after they knew it was contaminated with anthrax.

Christopher J. Farrell, the group's director of investigations, said he was disappointed by the report. "It glosses over inconvenient facts and lacks sufficient detail to accurately reflect the facts of what happened at Brentwood," he said.

The Brentwood Road plant was shut in October 2001 after two letters destined for Capitol Hill contaminated it with the deadly bacteria. The building was fumigated with chlorine dioxide gas in December 2002 and reopened a year later.

Renamed in honor of Joseph Curseen Jr. and Thomas Morris Jr., the two postal workers who died, the red-brick building has about 2,000 employees handling 3.5 million to 4.5 million pieces of mail a day.

The GAO, the investigative arm of Congress, examined the Postal Service's response to contamination at the D.C. plant and other processing and distribution centers in Connecticut, New Jersey, Florida and New York.

The 77-page report was done at the request of Rep. Christopher H. Smith (R-N.J.), Sen. Joseph I. Lieberman (D-Conn.) and Del. Eleanor Holmes Norton (D-D.C.).

The GAO report says "actions to protect postal employees were delayed" at the Brentwood Road NE facility.CURSEENMORRIS