Anthrax fear grows as 31 Senate staff test positive

America's political core was dealt a second shocking blow yesterday with the news that 31 Senate employees had tested positive for anthrax ­ prompting legislators to order an unprecedented shutdown of part of the Capitol.

Congressional leaders decided to close the House of Representatives and send home House members and staff until Tuesday. Even though the anthrax powder to which the 33 people were exposed was mailed to the Senate part of the Capitol, senators chose to carry on working. In New York, George Pataki, the state Governor, revealed that traces of anthrax had been found in his offices and his staff were being treated with antibiotics.

While officials admit there is little risk of those who tested positive becoming infected, news of the extent of the exposure has again dented the confidence of America. After a report that claimed the anthrax at the Capitol was finely milled and of a pure or "weapons" grade quality, probably manufactured by experts, anxiety over bioterrorism rose across the country.

Dennis Hastert, the Speaker of the House, initially said traces of the bacteria had been found in the building's ventilation system, adding to fears that it could have spread throughout the Capitol. The ventilation system was later confirmed to have tested negative, though Mr Hastert still proceeded to close the House. There was also confusion as to the strength of the anthrax. Mr Hastert said: "To ensure safety, we thought it best to do a complete sweep, an environmental sweep."

The anthrax at the centre of the scare was found in a letter posted to the Senate Majority leader, Tom Daschle, and opened on Monday. Last night, two employees of the Democrat senator Russell Feingold were revealed to have tested positive to anthrax exposure.

Traces of anthrax have been found in the Senate postroom, which is next door to Senator Feingold's offices. Despite this, Mr Daschle decided the Senate should continue to work. "We will not let this stop the work of the Senate," he said. "There is absolutely no evidence of infection at this point. All of those who had this positive nasal swab have been on antibiotics for some time and the good news is that everyone is OK."

Whoever is behind the anthrax scares, they have been successful if their intention was to create panic ­ America is in a state of unease not seen for a generation. Much of the anxiety in Washington centres on doubts over how to respond to the anthrax scares. "It has been a pretty crazy morning," said one Capitol Hill employee.

In Britain, where there have been several false alarms, David Blunkett, the Home Secretary, said new anti-terrorism laws could be amended to include tougher penalties for hoax terrorism. Health authorities were given guidelines on how to deal with botulism, bubonic plague and smallpox. Professor Liam Donaldson, the Government's chief medical officer, urged people not to panic, saying there was "no specific threat". He also condemned hoaxers, who put extra pressure on emergency services.

Meanwhile the American military campaign continued in Afghanistan, with waves of low-level raids. A fuel dump in Kabul exploded, forcing several Taliban tanks to evacuate. Columns of smoke rose in the east of Kandahar, which was subject to repeated strikes, and an army base near Jalalabad was hit.

Those injured in yesterday's raids on Kabul were taken to hospitals that have been without power for two days and are running short of supplies. In one, there were 10 victims, including two children. A boys' school in the city was hit by a bomb that failed to explode.

The Taliban's Voice of Shariat radio was silenced early in the campaign but the supreme leader, Mullah Mohammed Omar, broadcast to his forces by walkie-talkie, telling them they were fighting a holy war. Death was nothing to fear because they were sure to defeat the "great infidel. We will succeed whether we live or die," he said.

The Taliban said they had arrested a foreign man near the northern city of Kunduz who could be American or British. Qari Ahmedullah, the regime's intelligence chief, said the man was pretending to be mute, and his name was unknown. But he added: "We will not spare him ... We are trying to extract something from him."