Federal authorities arrested an 84-year-old former Army engineer Tuesday on charges of passing American military secrets to an Israeli agent in the 1980s, accusations that suggest that one of the most famous spy cases in U.S. history may have been more widespread than previously known.

Ben-ami Kadish, a U.S. citizen who worked at an Army base in New Jersey, acknowledged to FBI agents in an interview last month that he had given the Israeli agent 50 to 100 classified documents related to nuclear weapons, fighter jets and missiles, according to a criminal complaint filed in U.S. District Court in Manhattan.

Kadish was accused of reporting to the same Israeli government handler who was the main contact for imprisoned spy Jonathan Jay Pollard. Pollard is serving a life sentence in federal prison in North Carolina after pleading guilty to espionage charges in 1986 in a case that roiled relations between the U.S. and Israel.

The State Department, expressing dismay about the possibility of additional spying by "friends and allies," brought the matter to the attention of the Israeli government. Israeli Embassy spokesman David Siegel had no comment on the charges or any diplomatic fallout but acknowledged that "we were formally informed about the indictment by the relevant U.S. authorities."

Asked about the arrest, Arye Mekel, a spokesman for the Israeli Foreign Ministry, said: "We know nothing about it. We heard it from the media."

U.S. officials declined to discuss what new evidence they obtained that prompted them to target Kadish years after the alleged crimes were committed.

Kadish was charged with four counts of conspiracy, including allegations that he disclosed U.S. national defense documents to Israel and acted as an agent of the Israeli government. Appearing in federal court Tuesday afternoon, the Connecticut-born Kadish entered a plea of not guilty and was released. His lawyer, Bruce I. Goldstein, declined to comment on the charges.

According to the government court filing, Kadish told FBI agents last month that he believed providing classified documents to the agent would help Israel. Kadish told the FBI that he received no money for obtaining the documents, the filing says, and he said the agent gave him small gifts and occasionally bought dinner for him and his family at a restaurant in the Riverdale section of the Bronx.

Kadish worked as a mechanical engineer at the Army's Armament Research, Development and Engineering Center at the Picatinny Arsenal in Dover, N.J., from 1963 to 1990. The center housed a library of documents, many with classified information related to national defense.

Kadish allegedly told investigators that he was introduced to his would-be handler in the 1970s by his brother, who worked with the agent at Israel Aircraft Industries, a defense contractor for the Israeli government that is now known as Israel Aerospace Industries.

Kadish and the agent -- who was not charged and who was identified in court papers only as CC-1 -- allegedly met for the first time in New York. Though the subject of Kadish doing work for Israel did not come up at that meeting, the government says, Kadish eventually bought into the spy plan.

Working from lists of sought-after information prepared by the agent, officials alleged, Kadish began borrowing classified materials from the Army research library and took them home in his briefcase. The agent would then allegedly call Kadish and travel to his residence and photograph the documents in the basement. Kadish would later return the materials to the library, the government alleged.

According to the complaint, the documents included "information concerning nuclear weaponry" and "a major weapons system . . . a modified version of an F-15 fighter jet that the United States had sold to another foreign country." Another document dealt with the U.S. Patriot missile defense system, which Israel used to defend itself against Iraqi Scud missiles during the 1991 Persian Gulf War.

The alleged spying ended in 1985, although Kadish and his handler remained in e-mail and phone contact through March of this year, according to the government. The complaint says the Israeli called Kadish on March 20 after Kadish had been interviewed by the FBI earlier in the day. According to the complaint, the agent allegedly told Kadish in Hebrew to lie to law enforcement officials: "Don't say anything. Let them say whatever they want. You didn't . . . do anything. . . . What happened 25 years ago? You didn't remember anything."

In an interview the next day, the government said, Kadish told another law enforcement official that he had not spoken with the Israeli agent after the first interview. According to the complaint, the handler was employed from 1980 to 1985 by the government of Israel as the consul for science at the Israeli Consulate General in New York. It says he left the United States in November 1985 as the case against Pollard was building and has not returned.

The description of the handler in court documents matches that of Yosef Yagur, who was the New York attache at the time. Yagur has also been linked in court documents to the Pollard case. Reuters reported Tuesday that a woman in Israel identifying herself as Yosef Yagur's wife, when reached by telephone, said: "We're not speaking to journalists. Goodbye."

Pollard, a former civilian Navy intelligence analyst, pleaded guilty in 1986 to spying for Israel. The case strained U.S. and Israeli diplomatic relations, and the Israeli government long denied that he was its agent until after granting him citizenship in 1998. The case also laid bare the realities of how even close allies engage in frequent snooping on one another. Pollard has been held up as a hero in Israel, and there has been pressure over the years on American presidents to commute his life sentence.