Mr. Leibowitz, who declined to comment for this article, released the documents because of concerns about Israel’s aggressive efforts to influence Congress and public opinion, and fears that Israel might strike nuclear facilities in Iran, a move he saw as potentially disastrous, according to Mr. Silverstein.

While the American government routinely eavesdrops on some embassies inside the United States, intelligence collection against allies is always politically delicate, especially one as close as Israel.

The Federal Bureau of Investigation listens in on foreign embassies and officials in the United States chiefly to track foreign spies, though any intelligence it obtains on other matters is passed on to the C.I.A. and other agencies. The intercepts are carried out by the F.B.I.’s Operational Technology Division, based in Quantico, Va., according to Matthew M. Aid, an intelligence writer who describes the bureau’s monitoring in a book, “Intel Wars,” scheduled for publication in January. Translators like Mr. Leibowitz work at an F.B.I. office in Calverton, Md.

Former counterintelligence officials describe Israeli intelligence operations in the United States as quite extensive, ranking just below those of China and Russia, and F.B.I. counterintelligence agents have long kept an eye on Israeli spying.