Global jitters worsened after tests discovered traces of anthrax in white powder leaking from a letter at a Bahamas post office, and doctors diagnosed a new case of the deadly disease in the United States.

The Bahamas incident was the third case of parcel-packed anthrax outside the United States, after cases last week in Kenya and Argentina.

Of the hundreds of suspicious packets surfacing worldwide, most have so far been ruled false alarms. But authorities have little choice but to check each scare.

"Our country absolutely can't take this threat too lightly," Taiwanese President Chen Shui-bian said Monday, deciding to step up emergency drills and stockpile vaccines. "We must be prepared for every possible threat."

Concerns were much the same elsewhere.

In Finland and Denmark, the countries' main mail sorting centers closed when white powder was found leaking from letters. The Copenhagen shutdown delayed delivery of 75,000 letters, while the Finish workers were rushed to disinfecting showers.

Neighboring Sweden has pulled 142 suspicious items from the mail _ with the 57 packets so far tested all proving false alarms.

In Japan, 900 high school students were sent home after a powder-filled envelope was mailed to their school and police in the northern city of Sapporo were investigating white powder scattered on the bathroom floor of a government office. Police suspect pranks in both cases.

In Malaysia, just to be on the safe side, workers at the U.S. embassy in Kuala Lumpur were given antibiotics after the building received a letter with a powdery substance.

On Monday, Thai officials said they won't inform citizens about letters suspected of containing anthrax spores in the form of white powder. "It's not withholding of information, just that we won't talk about such letters unless we've confirmed those letters contained anthrax," Deputy Health Minister Surapong Suebwonglee said.

Trying to blunt the rash of fake anthrax threats, British officials said they will try to increase the penalties for hoaxers who scare the public with false warnings about chemical, biological, radioactive or nuclear weapons. Anti-terrorist legislation to be introduced in Parliament next month will include a provision that boosts time behind bars for such pranks to seven years, from six months.

India tried to soothe a nervous public Monday by issuing government guidelines on anthrax treatment to more than 50,000 health care centers across the country.

As of Sunday evening, the Indian government had received 42 reports of suspicious packages or powders. Samples from 15 tested negative, the others were still being examined.

In the United States, a Washington postal worker has fallen "gravely ill" from inhalation anthrax, a rare and lethal form of the disease, and five others are sick with suspicious symptoms.

The diagnosed man, who was not identified, is the third person in the United States to come down with the most serious form of the disease, where anthrax spores enter the respiratory system and lodge deep in the lungs.

Six others, including two postal workers in New Jersey, have been infected with a highly treatable form that is contracted through the skin.