As jittery residents of New York and Washington continued to prepare yesterday for a possible terrorist attack, Congress's senior intelligence committee member said there was "absolutely no reason" for panic and criticized the new Department of Homeland Security for not communicating better with the American public.

"Do not fall for hysteria and rumor," said Rep. Porter J. Goss (R-Fla.), a former CIA officer and chairman of the House intelligence committee who was given classified updates of the threat last night. "There is no justification, there's no more specificity to the threat" than there was Feb. 7, when federal officials raised the national threat level to orange, indicating a "high risk" of a terrorist strike.

Sen. John D. Rockefeller IV (D-W.Va.), vice chairman of the Senate intelligence committee, also expressed concern about the administration's handling of the situation and called on President Bush to address the public on the matter. Secretary of Homeland Security Tom Ridge scheduled a news conference for today to update the public on the terrorist threat.

The Homeland Security Department said its communications had been appropriate but acknowledged that it plans to issue more detailed guidance next week on how an already nervous public can better prepare for an attack.

Several administration officials with access to classified intelligence reports, said however, that intelligence agencies have become especially concerned about a possible attack today or over the weekend, and added Saudi Arabia to the three previously mentioned possible targets: New York, Washington and sites of Jewish importance.

Intelligence officials continue to believe that an attack would involve poisonous chemical or biological agents, or possibly a small radiological device, or "dirty bomb."

Federal authorities urged business leaders to recheck their workforces for possible al Qaeda sympathizers and asked operators of chemical plants, nuclear power facilities and other critical infrastructure to watch for suspicious activity or employees.

The FBI's National Infrastructure Protection Center posted a bulletin on its Web site Wednesday advising business leaders to review events that aroused suspicion, especially incidents in which their operations were the target of surveillance.

Members of Congress were told to gather a "go bag" of supplies, sensitive documents and key phone numbers in case of an attack, while staff members were given training this week on how to handle escape hoods that protect against biological or chemical substances.

Rep. Robert W. Ney (R-Ohio) said lawmakers were also instructed to keep a low profile, remove vanity license plates from vehicles and vary their routines.

Goss said he had answered questions from hundreds of worried lawmakers and staff wondering how they should prepare. He said he has told them to prepare for a rainy day: cash on hand, bottled water, flashlight and extra batteries. "It would be helpful to have more specific guidance," he said.

Homeland Security officials prompted a run on those items, as well as plastic sheeting and duct tape, after a news briefing Monday to emphasize the need for the public to take such preparations seriously.

Preparations were perhaps most evident in New York City yesterday, where police diverted trucks to mile-long single lanes over East River bridges, briefly closed the Brooklyn Battery Tunnel and searched every tunnel and bridge.

Police Commissioner Raymond W. Kelly told a news station that the city has ratcheted up its level of preparedness to just short of "red," the top level on the Homeland Security Department's color-coded index, which would indicate an imminent attack. Kelly said he has redirected 200 officers from neighborhoods to reinforce potential targets around the city.

Police have placed shoe-box-size sensors at several subway stations to test for the presence of chemical and biological agents, and heavily armed police teams are rotating throughout the city. The National Guard was helping patrol subways and streets.

"There are gradations within orange, and New York City is at the high end of orange," Kelly said.

But later in the day, Mayor Michael Bloomberg emphasized normalcy. The morning newspapers carried reports that city officials have warned hospitals to prepare for cyanide attacks on the subways, but Bloomberg shook his head when asked if such precautions came in response to a particular threat.

"No, not that we know of, period," he said. "The real world is that you don't know."

The bottom line, Bloomberg added, is that "you don't have any significant risk to your life as long as we do our job."

Several hospitals acknowledged they were reviewing their procedures for treating exposure to chemicals and "among those are, yes, cyanide," said Susan Waltman, senior vice president of the Greater New York Hospital Association. She noted that since Sept. 11, 2001, hospitals have paid special attention to updating their stockpiles of antidotes for various biological and chemical agents. Waltman said the federal government has speeded up this process in the past week.

Hardware stores reported a run on duct tape and other items recommended by the Homeland Security Department. New Yorkers, who had enjoyed a period of relative calm since the last nationwide alert on the one-year anniversary of the Sept. 11, 2001, attacks, were again talking about terrorism.

"There's a sense of dread everywhere," said Laura Popper, a Manhattan pediatrician. "Some parents aren't sending their littler children to school. There's a pressure that just keeps building. I'm churning inside just like everyone else."

Staff writers Susan Schmidt, Ceci Connolly, Spencer Hsu, Allan Lengel and John Mintz contributed to this report.