Counterterrorism officials have specific information about a possible terrorist attack against the United States from a broad intelligence spectrum, including, sources said, information about the al Qaeda operatives masterminding the effort.

While government officials said they don't know when or where the terrorists may attempt to strike, they have been focused on the possibility that attacks could begin at the conclusion of the hajj, the annual pilgrimage to Mecca made by Muslims that ends today.

U.S. sources said yesterday the government has tracked movements of al Qaeda money it believes is being used to finance the threats against the United States and its interests abroad. Information is coming from multiple sources, including foreign intelligence services, human sources, electronic intercepts and e-mail.

"It's very specific. It's known people," said a counterterrorism official. He and other sources said Sept. 11, 2001, mastermind Khalid Sheik Mohammed is believed to be among those involved in planning the new attacks, which they believe may be directed at Washington and New York.

On Friday, the government raised the threat warning level to reflect a "high risk" that al Qaeda will attack U.S. targets here or overseas. The designation was raised to orange on the five-tiered, color-coded threat scale, second only to red, which indicates an imminent or ongoing attack.

New York Police Department officials traveled to Washington Tuesday to meet with FBI officials to discuss the threat. A spokesman for Police Commissioner Ray Kelly said yesterday the city has no plans to raise its own threat assessment to code red.

On Friday, the federal government warned that newly acquired intelligence indicates a "high risk" of attack by the al Qaeda terrorist network against U.S. targets at home and abroad. Officials have said they are particularly concerned about chemical, biological or radiological weapons, including ricin, cyanide and "dirty bombs" that would spread radioactive debris over a wide area.

Department of Homeland Security officials urged Americans to take precautions against the possibility of an attack, including designating a sealed-off safe room in their homes and stockpiling food and water.

The increased threat level coincides with U.S. military planning for a possible war with Iraq, which could break out in the next few weeks, as well as the end of the hajj, an event specifically mentioned by CIA Director George J. Tenet in testimony before a congressional committee Tuesday. One source familiar with the government's intelligence assessment said officials are especially focused on a 10-day period, commencing with the beginning of the five-day hajj last Sunday.

Local authorities across the country have stepped up security in response to the threat warning, particularly in New York and Washington, where subway systems are seen as a possible target for a nerve gas attack.

In the District this week, Metro Transit Police administrators left their desk jobs and began patrolling stations during the morning and evening rush periods.

Transit Police Chief Polly Hanson said that the extra patrols will continue indefinitely and that they are a way to increase police presence in the subway. Metro's 11 bomb-sniffing dogs also have been working more, she said.

Staff writers Brooke A. Masters and Dana Priest contributed to this report.