The U.S. Customs Service has placed all 301 ports of entry into the United States on high alert after the arrest of an Algerian in Washington state who had crossed the border from Canada with more than 100 pounds of bomb-making supplies and a sophisticated detonating device in a rental car.

Ahmed Ressam, 32, a resident of Montreal who had been denied refugee status by Canadian officials because of his alleged links to a terrorist group known as the Islamic Armed Group (GIA), was arrested by customs officials in Port Angeles, Wash., five days ago and charged in Seattle on Friday with transporting explosives into the United States, providing false identification and lying to authorities.

Andre Poirer, a spokesman for the Montreal police, said last night that his department has information possibly linking Ressam to Karim Said Atmani, who was extradited by Canada to France on charges that he participated in a Paris subway bombing in 1995 that killed four people and injured 86.

Poirer also said that authorities in Montreal are investigating whether Ressam is linked to a theft ring in the city suspected of funneling money to radical Islamic groups around the world.

Montreal police announced Thursday they had arrested 11 men, most of Algerian origin, over the past four months for thefts during the previous two years that netted more than 5,000 items, including computers, cellular phones, passports and credit cards. Based on information from Interpol and French police, Montreal police said they have concluded that the real purpose of the ring was to generate cash to help finance Muslim extremist groups.

"There are terrorists in Montreal," said Claude Paquette, an investigator. "They are doing things like financing their fighting friends overseas."

U.S. authorities, meanwhile, intensified efforts to find an accomplice who apparently had been with Ressam at a motel in British Columbia for three weeks before Ressam's passage into the United States. The FBI is also investigating links agents believe Ressam has to other Islamic extremists in the United States, one U.S. official said yesterday.

Harvey Kushner, a terrorism expert at Long Island University who has close ties to federal law enforcement officials, said he had been told by authorities that a search for Ressam's accomplice extends from the West Coast to New York.

"They're extremely concerned," Kushner said, adding that the bomb-making equipment and timing device Ressam had in his possession are virtually identical to those used by associates of Osama bin Laden, the millionaire Saudi militant based in Afghanistan.

U.S. officials have yet to establish a definitive link between Ressam and bin Laden, but one senior U.S. official said yesterday that "there is evidence that would lead me to believe that he has associations with bin Laden, or people who have associations with bin Laden."

Vincent Cannistraro, former head of counterterrorist operations at the CIA who now works as a security consultant, said U.S. law enforcement and intelligence officials believe Ressam is tied to bin Laden but have thus far refused to describe the exact nature of the connection.

What is clear, Cannistraro said, is that Ressam's arrest has left law enforcement and intelligence officials deeply concerned about possible terrorist attacks on U.S. soil as millennium celebrations approach.

"It is a little scary, because they weren't looking here," Cannistraro said. "They were looking abroad."

Cannistraro said the detonation device found in Ressam's rental car--circuit boards linked to a Casio watch and a nine-volt battery--is "the method they teach in [bin Laden's] camps in Afghanistan--and the Casio device turned up in one of the Moscow apartment bombings" thought to have been carried out earlier this year by Islamic radicals.

Canada's Globe and Mail, quoting a source in Washington, said U.S. counterintelligence agents had alerted the Royal Canadian Mounted Police about Ressam's presence in Vancouver and that the Mounties had been keeping an eye on him.

Ressam and the accomplice reportedly checked into the 2400 Motel in Vancouver three weeks ago, paying cash for the $325-per-week suite of two rooms, a kitchen and bath.

On Friday, as Ressam made his first appearance in a Seattle courtroom, Mounties staked out his apartment house at 1250 Fort St., in Montreal's East End, telling reporters they were awaiting a search warrant.

Finally, about 9 p.m., after evacuating the building and cordoning off the block, a bomb squad entered the apartment looking for any other explosive devices or materials, according to spokesman Leo Monbourquette. After a two-hour search that turned up no explosives, residents were allowed back in the building. Monbourquette would not say what other items were found in the apartment.

Ressam's arrest and the disclosure by Montreal police of the theft ring tied to Islamic militants came just days after the arrest of 14 bin Laden associates in Jordan and Pakistan for allegedly plotting attacks on tourist sites abroad and American travelers during the millennium celebrations.

Bin Laden has been indicted in the United States on charges of conspiracy and murder in the 1998 bombings of U.S. embassies in Kenya and Tanzania that killed more than 220 people. Based on intelligence reports of terrorist activities overseas tied to millennium celebrations, the State Department issued a worldwide warning to travelers a week ago, saying terrorist attacks that could take place any time before the end of the year.

Loeb reported from Washington, Pearlstein from Toronto.