Scare on Capitol Hill as ricin is discovered in office of Senate leader

Three Senate buildings in Washington were closed and the business of law making was disrupted yesterday after the deadly poison ricin was found in the office of Bill Frist, the majority leader.

The scene on Capitol Hill was reminiscent of the days after the attacks of 11 September 1981 when anthrax was found in the complex. Many staff members were told to stay at home and all hearings and committee meetings were cancelled as bioterrorism experts looked for evidence, and decontaminated the affected areas.

Police told members of Congress to stop opening their mail and some senators abandoned their normal offices to work elsewhere in the complex until the scare was over.

Debate continued in the Senate chamber itself, however, and Mr Frist paused to confirm to colleagues that the powder had indeed been identified as ricin, which can cause breathing difficulties and death. "Somebody in all likelihood manufactured this with intent to harm," he said.

Investigators said they had not pinpointed the envelope or package that had contained the powder.

In Connecticut, a postal worker found an unidentified white substance seeping from an envelope that was addressed to the Republican National Committee. Investigators were examining the substance.

Officials at the Centres for Disease Control and Prevention in Atlanta said they were reasonably confident that no one in Mr Frist's office had been made ill by the ricin.

"As each minute ticks by, we are less and less concerned about the health effects," Dr Julie Gerberding, the centres' director, said.