Senate evacuated in ricin scare

Police ordered an evacuation of the offices of a senior US politician after white powder tested positive for the deadly poison ricin.

The mysterious substance was found in an envelope sent to the Washington office of Republican Senate leader Bill Frist.

Officials said last night that two out of three initial tests had shown it could be ricin, which is made from the castor bean plant, and can kill within days if inhaled or swallowed.

US police described the powder as a "hazardous substance" and said it was now being tested further at an army research laboratory at Fort Detrick in Maryland, with the results due later today.

The powder is believed to have been found in an envelope with a letter to Senator Frist, sent to his office on the fourth floor of the Dirksen Senate office building.

It was found late yesterday afternoon, with 16 staff ordered to leave and decontaminated. The envelope had already been passed through sorting machines that irradiate all post to the US Congress as a precaution against bio-terrorism.

Senator Frist said: "Everybody is fine. We don't expect anybody to get sick."

Ricin has been linked to al Qaeda, with equipment and instructions to produce it found at terrorist training camps in northern Iraq by US forces last year.

Seven men of North African origin were arrested last year when police found traces of ricin at a flat in north London.

The highly toxic poison has no known antidote, with a dose the size of a pinhead enough to kill one person. If inhaled, it causes death from respiratory and circulation failure. Ricin can also be injected, leading to failure of the body's major organs within two days.

Traces of ricin were also found last October in a metal container at a postal service sorting office in Greenville, South Carolina.

It was accompanied by an "angry note" about regulations on the road haulage industry, with the FBI saying at the time there was no obvious terrorist connection. A reward of around £70,000 has already been offered for the arrest and conviction of those responsible.

Government offices in Washington have been on high alert since five people died from anthraxcontaminated letters at the end of 2001.

Several of the letters were sent to prominent politicians at the Dirksen building, which was closed for several days for decontamination. Two post office workers died from handling letters contaminated with anthrax. Law enforcement agencies have failed make an arrest in the case.