A federal grand jury in New York indicted a Montreal man yesterday for his alleged role in a terrorist conspiracy tied to explosives ferried into the United States by an Algerian arrested last month in Seattle.

Mokhtar Haouari is a new suspect and the sixth person to be charged by federal authorities since the arrest on Dec. 14 in Port Angeles, Wash., of Ahmed Ressam, an Algerian national from Montreal whose rented car contained substantial liquid and powdered explosive chemicals.

Haouari is in custody in Canada, law enforcement sources said, although they would not specify in which city. He is not believed to be the group's ringleader, though his actions indicate he was directing another indicted suspect in the case, Abdel Ghani, who was arrested Dec. 30 in New York.

The two men's association dates to at least November, when phone records indicate that Ghani placed calls from New York to the cellular phone and business of Haouari in Montreal, yesterday's indictment states.

Then, in December, Haouari asked Ghani to travel to Seattle to assist Ressam, according to the indictment. On Dec. 11, Ghani traveled to Seattle. Between Dec. 10 and Dec. 15, Ghani used a fraudulent bank card to withdraw money from automated teller machines in and around New York and Seattle, the indictment alleges.

In late December, after the arrest of Ressam, Haouari instructed Ghani to discard his pager and to change his telephone numbers in what the government termed Haouari's giving "material support and resources" and concealing and disguising the group's plans to carry out a terrorist bombing.

In addition, Haouari is alleged to have played a role in organizing certain key aspects of the group's activities. "At various times in or about October 1997 to the present, Mokhtar Haouari, the defendant, provided members and associates of a terrorist group with various means of false identification and forged identification documents," the indictment states.

The terrorist group was not named in the indictment. Court filings in other arrests in the case, including that of Lucia Garofalo and Bouabide Chamchi in Burlington, Vt., indicate that the group may have been a spinoff of the Armed Islamic Group, or GIA, a Muslim underground organization that seeks to topple the army-backed government in Algeria. Its motives in mounting an attack on U.S. soil have not yet been described by law enforcement officials, who say they have not determined the group's motives.

The other arrest tangentially connected to the case so far was that of Abdel Hakim Tizegha on Dec. 24 in Bellevue, Wash. He was charged with immigration violations; no terrorism-related charges were filed against him. Tizegha entered the Canadian province of British Columbia while Ressam and another Algerian allegedly were mixing explosives in a Vancouver, B.C., motel.