WASHINGTON, March 18 — Almost two years before the Federal Bureau of Investigation publicly admitted this month that it had ignored its own rules when demanding telephone and financial records about private citizens, a top official in that program warned the bureau about widespread lapses, his lawyer said on Sunday.

The official, Bassem Youssef, who is in charge of the bureau’s Communications Analysis Unit, said he discovered frequent legal lapses and raised concerns with superiors soon after he was assigned to the unit in early 2005.

Stephen M. Kohn, the lawyer for Mr. Youssef, said his client told his superiors that the bureau had frequently failed to document an urgent national security need — proving “exigent circumstances,” in the bureau’s language — when obtaining personal information without a court order through the use of “national security letters.”

Mr. Youssef said his superiors had initially minimized the scope of the problem and the likely violation of laws intended to protect privacy, Mr. Kohn said.