U.S. law enforcement officials yesterday arrested people in New York and Boston and questioned dozens of others nationwide in an effort to uncover and disrupt a possible network of Algerians suspected of planning terrorist attacks during the nation's millennium celebrations.

Federal and local law enforcement officials also disclosed that a Canadian woman arrested last week trying to cross the border into Vermont, an Algerian man caught earlier this month trying to smuggle explosives into the United States, and a third person arrested in New York yesterday were all linked to the same Algerian terrorist organization.

From papers filed in three different courts yesterday, it appeared that the group had an elaborate plan involving false passports, aliases and a secret rendezvous to leave a rented car filled with explosives at a drop-off point in Seattle, where another member of the network would take charge of the vehicle.

Known as the Armed Islamic Group, the Algerian terrorist organization has never targeted the United States or Americans before, prompting U.S. officials to speculate that some of its members might be acting on their own or in league with other Islamic groups at odds with the United States, such as one sponsored by exiled Saudi extremist Osama bin Laden.

FBI officials said they had not identified any specific U.S. city or site that was the focus of the attack. But sources said investigators were worried that the people caught have accomplices already inside the United States who were part of the plan to carry out terrorist attacks.

"When you start getting all these lines coming together, that tends to suggest much wider operational planning than initially suspected," said Vince Cannistraro, former director of counterterrorism at the CIA. "There is a concern that there are other people who are part of this network . . . and that materials needed for a violent event are already here. That's why there's an effort to roust anyone who might have connections to those groups."

A joint terrorism task force in New York said yesterday it had uncovered one of those alleged connections. Abdel Ghani was detained at his Brooklyn apartment after police found his name and the apartment's phone number on a piece of paper when they arrested Ahmed Ressam, the man caught carrying explosives into Washington state on Dec. 14.

In a court filing, federal prosecutors said Ghani traveled from New York to Seattle using the alias Eduardo Rocha and was supposed to meet Ressam there. Ressam was to leave his rented car filled with explosives at a specified location, where it would be picked up by another member of the group, the complaint says.

Ghani and Ressam were planning to go to Chicago next, but their trip was aborted after Ressam was arrested.

In Vermont, a federal magistrate ruled yesterday that Lucia Garofalo, who had been arrested last week while attempting to enter the country from Canada at a remote border crossing, should be held without bail after the Justice Department disclosed that she had strong links to the same terrorist group, known by its French acronym GIA.

"As someone who possesses such close ties to terrorist organizations, and especially in light of the arrest of Ressam contemporaneously with her attempts to smuggle other Algerians into the United States, Garofalo appears to present a substantial risk that her actions are in aid of terrorism," said U.S. Attorney Charles R. Tetzlaff.

Meanwhile, FBI agents fanned out across the country questioning individuals who they believed may have more information about precisely what Ressam intended to do with the dangerous explosives he was transporting. Individuals were questioned in Washington state, California, New York, Texas, Massachusetts and elsewhere.

"People are being interviewed whose names have surfaced from a variety of sources during the course of the current investigation of Ressam," said FBI spokesman John Collingwood. "That doesn't mean they are subjects of investigations. It means they may know something or be in a position to help."

But some terrorism experts said the FBI seemed intent on eliminating possible terrorist threats even if they needed to use immigration charges to detain suspects.

"There are probably some preemptive arrests," said Bob Blitzer, former head of domestic counterterrorism for the FBI. He said the FBI would "nail them for anything they can, just to get them off the streets." Others said this raised concerns about possible civil liberties violations.

Five men ranging in age from 26 to 35--at least three of whom are believed to be of Algerian descent--were arrested and detained in the Boston area today, federal authorities said. All had been sought for questioning as part of an ongoing FBI terrorism investigation, but were subsequently arrested on immigration violations, authorities said.

"The message should be clear that we're going to pursue any and all information that we can to ensure the public's safety," said Boston Police Commissioner Paul F. Evans.

The common thread for the arrests in Brooklyn, Washington state and Vermont was the GIA, which has been held responsible for some of the bloodiest attacks in Algeria's civil war and for bombings in France earlier this decade. Counterterrorism experts said that GIA splinter groups might be working independently for bin Laden. Terrorism experts said that many GIA members received training in Afghanistan, where bin Laden is based.

Prosecutors in New York quoted a confidential source saying that Ghani had acknowledged spending time in Afghanistan. Prosecutors also said that the source quoted Ghani and another associate as having "agreed in a recent conversation in sum and substance that Allah will shake up this world, that a new generation will punish America, and that Islam's renaissance will rise from Algeria."

In Vermont, prosecutors alleged that the woman arrested there, Garofalo, had traveled to the United States at least twice this month before being detained last week along with an Algerian man carrying a false passport. They said that she has access to false passports and should be held without bail because of her ties to Algerian terrorist groups. While living on welfare in Canada and claiming to have just $8 in her bank account, Garofalo had taken five trips to Morocco, two each to France and Germany, and visited Libya and Italy many times, the filing said.

While Garofalo claimed her travel was paid for by her "wealthy mother," her trips around the world allegedly were funded by the GIA. In addition, she had a cellular phone and a car registered both in her name and that of Brahim Mahdi, a member of the Algerian Islamic League, another organization associated with the Algerian Islamic opposition. The organization is run by Mourad Dhina, who has been identified as an international Algerian arms dealer who has shipped arms and funded terrorist organizations in Europe and Algeria.

Blitzer and Cannistraro said they believed Americans should not change their normal holiday plans. "When you do that," said Blitzer, "that's when [terrorist groups] have won . . . a psychological victory."

Staff writer Lynne Duke in New York and special correspondent Pamela Ferdinand in Boston contributed to this report.