Two leaders of a mosque in Albany, N.Y., were arrested today in an FBI-led sting operation on charges related to a purported terrorist plot to buy a shoulder-fired missile, which was to be used to assassinate a top Pakistani diplomat, authorities said.

In a press conference in Washington, Deputy Attorney General James B. Comey said he hoped the arrests would "send a disruptive message" to any terrorist plotters, raising suspicions among them about the real identities of their accomplices.

Comey played down the arrests to some extent, stressing that neither of the two Muslim immigrants caught in the sting had been plotting to carry out any act of terrorism personally. Instead, the government charges, they had been involved in a money-laundering scheme connected with the proposed sale of a shoulder-fired missile by an undercover informant.

Taken into federal custody today were Yassin Aref, 34, the imam of Albany's Masjid as-Salaam mosque, and Mohammed Hossain, 49, the mosque's founder and owner of an Albany pizza parlor. Aref, whose name is spelled "Ya Seen Arif" on the mosque's Web site, is reportedly a Kurdish immigrant from Iraq. Hossain is a naturalized U.S. citizen who immigrated from Bangladesh nearly 20 years ago.

Federal officials said Aref and Hossain were being charged with providing material support to terrorism by conspiring to help a man they believed was a terrorist launder money from the sale of a portable missile.

A joint task force led by the FBI arrested the two men at their homes and raided the mosque following an investigation that began more than a year ago. Federal law enforcement officials quoted by news agencies said the men had ties to Ansar al-Islam, an extremist Muslim group with connections to the al Qaeda network and to Abu Musab Zarqawi, a Jordanian terrorist operating in Iraq.

Comey told reporters he could not immediately confirm any connections to Ansar al-Islam, but he said the government may soon elaborate on the background of one or both defendants at a detention hearing.

Hossain's wife, Mossamat Hossain, denied that her husband had anything to do with terrorism and professed to be baffled about why he was arrested, the Associated Press reported. She said a half dozen agents stormed her family's apartment at about 1:30 a.m. today just as her husband returned from New York City, where he bought her mother a plane ticket for Bangladesh.

"My husband has a very clean heart," Mossamat Hossain told the Albany Times Union newspaper. "He doesn't hide anything." The paper quoted her as saying agents seized the hard drive from her husband's computer, various personal and bank account records and $6,000 in cash in the raid on their apartment above their Little Italy pizzeria.

The wife of Aref, Zuhor Jalal, also denied that her husband was involved with terrorism, the AP reported. She said she and Aref, both natives of Kurdistan, lived in Syria for five years before coming to the United States "for freedom and job."

In a statement, the Air Line Pilots Association, which represents 64,000 airline pilots in the United States and Canada, applauded the arrests. Capt. Dennis Dolan, first vice president of the association, said that "the most effective defense against this kind of threat is to take the man out of the MANPAD," or man-portable aid defense weapon, as shoulder-fired missiles are called. After the Sept. 11, 2001, terrorist attacks, "we have placed too much emphasis on chasing things rather than people," he said. "Regardless of how much technology and screening we put in place, the first and best line of defense will always come from good intelligence and a focus on the terrorists themselves."

But the Washington-based Council on American-Islamic Relations expressed concern that the case could help "those with political or religious agendas to smear Muslims and to demonize Islam."

The government's allegations against the two Albany men "are deeply troubling to the American Muslim community," the nation's largest Islamic civil liberties group said in a statement. Their alleged actions "should not be used to tar an entire community with the brush of terrorism," it added.

"This is not a case connected to the current terrorist threat," Comey said in Washington. "This is not a case where the defendants were discovered plotting terrorist violence." He added that it was "not the case of the century," but "a solid case" that "sends an important message" to potential plotters.

"We really do want the bad guys to worry that anybody they're dealing with might be our guys," Comey said. "We want the bad guys to worry about us."

Comey said a "cooperating witness," a non-American he described as a "criminal" who was working with the government to obtain a reduced sentence on a conviction for document fraud, befriended Hossain, who at one point asked him to help obtain a fake New York driver's license for Hossain's brother.

The informant told Hossain he was engaged in buying ammunition for a Pakistani terrorist group and, at one meeting, produced a shoulder-fired missile that he said he was selling, Comey said. The informant told Hossain the missile was to be used to assassinate the Pakistani ambassador in an attack on that country's consulate across the street from the United Nations in New York in retaliation for Pakistan's role in the war on terrorism, Comey said.

If convicted, Hossain and Aref each face up to 70 years in prison and a $750,000 fine.

In a press conference in Albany, New York Gov. George Pataki (R) said of the case, "The fact is there are terrorists among us." He said he wanted to assure the public that federal, state and local authorities "are taking this threat to our freedom very seriously" and will continue to be "proactive" in the war on terrorism.

"Today we see here again in the capital region those among us who seek to help terrorists conduct horrible acts against the people of America and against our freedom," Pataki said.

He said he could not provide details of the case against the two mosque leaders, but noted that there was no apparent connection between the Albany arrests and a heightened terrorism alert in New York City based on information obtained from recent arrests of al Qaeda militants in Pakistan.

Albany Mayor Jerry Jennings said the case is "a prime example of good cooperation" among federal, state and local law enforcement. "We want people to feel good about what happened today, because we were on top of it," he said.

Aref and Hossain allegedly were involved in an aspect of the purported plot involving money-laundering, from which they believed they stood to gain thousands of dollars, authorities said.

The plot allegedly involved the sale of a shoulder-fired missile from China, but no such missile ever changed hands.

Concerns that terrorists could use missiles to shoot down airliners grew after attackers fired two portable SA-7 missiles at an Israeli commercial plane during takeoff from Mombasa, Kenya, in November 2002, narrowly missing the aircraft.

In a multinational sting operation last year, a British arms dealer of Indian origin, Hemant Lakhani, was arrested by the FBI in Newark, N.J., after he took delivery of a Russian SA-18 Igla missile that he had arranged to sell to an undercover FBI agent posing as a Muslim extremist. Two other persons were later arrested in New York City in connection with the plot, in which the missile was to be used to shoot down a U.S. airliner.

That case involved cooperation from British and Russian intelligence agencies. The missile, which had been rendered harmless by Russian authorities, was shipped to the United States disguised as medical equipment.

In a recent interview, Hossain, the Bangladeshi immigrant arrested today, told the Times Union newspaper in Albany that he came to the United States with his wife and small son in 1985 to escape the poverty of his homeland and started out working as a dishwasher in diners. Eventually he saved enough to start his own pizza shop in 1994.

"I'm proud to be an American," the newspaper quoted him as saying in one of a series of profiles of people who live on Albany's Central Avenue. "When I was in high school in Bangladesh, I looked at a map of America and I dreamed of coming to this great land. Since I've been here, opportunity has kissed my feet. Hard work has done the rest."

He regretted, however, that his wife, who has a graduate degree in sociology from Bangladesh, could not find work in that field, and he said he longed to sell the pizzeria so that she could go back to college and earn a doctorate.

"I feel guilty every day of my life," the Times Union quoted Hossain as saying. "She has a master's degree and she works all day in a pizza shop."