A grand jury convened in New York to help pursue those responsible for last week's terrorist attacks as the federal investigation intensified Sunday, with authorities holding at least two men arrested as material witnesses and expanding their list of people being sought for questioning to about 175.

At the same time the Justice Department, responding to what it depicts as obstacles slowing its investigation, prepared to seek special new tools from Congress, including broader wiretap authority and easing of other restrictions on the FBI's investigative powers. Concerned that these will be opposed by civil libertarians, department officials may ask for such authority only for the duration of this investigation.

As investigators began plowing through their list of those who may have useful information on the hijackings, a Tribune review of the original list of 100 people wanted for questioning suggested that many in fact had little of interest to contribute. Some were merely passing acquaintances of the perpetrators, and the results illustrate just how broadly the FBI is casting its net.

Public records show that two of the men held for questioning in connection with the attacks listed an apartment in Chicago among their addresses from 1998 until last June. The men, who were arrested on an Amtrak train in Texas last week, were reported to be cooperating with federal agents in New York.

In Washington, senior intelligence officials told key lawmakers Sunday that the terrorists who planned Tuesday's attacks could be planning further strikes against American targets, and did not rule out the possible use of chemical or biological weapons.

"The assessment of the intelligence community is that the plan of the terrorists had more than just Tuesday," Sen. Bob Graham (D-Fla.), chairman of the Senate Intelligence Committee, said after a CIA briefing.

The FBI has yet to name anyone a suspect in the hijackings other than the 19 who seized the four planes and died in the crashes at the World Trade Center, the Pentagon and a field in rural Pennsylvania. But frenzied investigative activity stepped up across the country as an extraordinary task force of more than 4,000 FBI agents aided by 3,000 support personnel hunted those who might have provided aid or shelter to the terrorists.

One focus of FBI activity over the past few days has been Jersey City, N.J., home to a large Arab-American community and just across the Hudson River from lower Manhattan. The FBI was led to Jersey City after it seized two men from an Amtrak train in Texas last week in connection with the attacks.

Both men lived in Jersey City, and interviews with the two led authorities Saturday to raid a 13-unit brick apartment there, said FBI agent Sherri Evanina. The raid resulted in two men being led away in handcuffs, putting them among the 25 individuals who have been detained but not charged in connection with the deadly hijackings.

The neighborhood around the building is predominantly Egyptian, and Arabic stores and restaurants pepper the area. The FBI searched a second-floor apartment that records suggest was home to both of the men detained in Texas.

`Perfect tenants'

The building landlord said Sunday that the two residents were "perfect tenants" who claimed to have worked at newsstands in New York and always paid their $480 monthly rent promptly.

Ayub Ali Khan and Mohammed Jaweed Azmath, both of whom are from India, have leased the small, one-bedroom apartment, No. 202, for the past six or seven years, said the landlord, who requested anonymity.

However, public records show that, as recently as last June, both men listed their residence as an apartment at 1025 W. Hollywood Ave. on Chicago's North Side.

The raid on the apartment building in Jersey City started about 11 a.m. Saturday with agents smashing through a glass-and-steel security door to gain access to the building, according to residents.

"I just heard the noise and saw people running up the stairs," said Harish Singh, a 42-year-old computer programmer whose first-floor apartment is a few steps from the security door.

Singh and other residents said they were questioned by the FBI and were shown grainy black-and-white photographs of two Arab men. Residents said agents also questioned them about their own immigration status and demanded to see their personal papers.

FBI agent Evanina declined to comment on why two other men were arrested at the building during the search, which lasted about two hours. She said only, "We were not anticipating encountering the other two."

A crowd gathered outside the building chanted "U.S.A., U.S.A." as the men were taken away in handcuffs, said Singh and other residents.