The securities law expert appointed by a federal judge to review the operations of First Jersey Securities Inc. has resigned, apparently because of a potential conflict-of-interest problem regarding a book he wrote with one of the firm's lawyers.

But a top official of the Securities and Exchange Commission, which has doggedly pursued First Jersey and its flamboyant founder and president, Robert E. Brennan, over the past decade for alleged securities law violations, said the special consultant's resignation did not stem from the book. However, the official, Ira Lee Sorkin, SEC's New York regional administrator, would not disclose any other reason for the resignation of the consultant, Southern Methodist University Law Professor Alan R. Bromberg.

"Suffice it to say that we suggested that he withdraw," Sorkin said. "It had nothing to do with the book, and in no way is there any suggestion to impugn his integrity and professionalism, which is of the highest order."

Bromberg could not be reached for comment.

The two sides will now try to agree on a new consultant to the company, who must then be approved by U.S. District Judge Milton Pollack, a process that could take several weeks.

The role of the consultant was included in a settlement reached two weeks ago by the SEC and Brennan, in which the SEC dropped longstanding charges of securities manipulation and fraud against the fast-rising discount brokerage firm and its president. The company and Brennan were enjoined from violating securities law, and Bromberg was appointed to conduct a 90-day study of the company and recommend to the court any changes that might be needed in First Jersey's operations.

The disagreement over the circumstances of Bromberg's departure from the case are in keeping with the long-running feud between the SEC and Brennan, in which the two sides have frequently been unable to agree on simple facts of the case. And when the settlement was announced, both sides claimed victory.

Yesterday, Brennan said that the SEC had indicated last week, in a hearing before Judge Pollack in which Bromberg withdrew from the case, that Bromberg had requested to leave the case himself, because of the possible conflict over the book. Sorkin could not be reached for comment on what was said before the court.

Both sides agree that they knew about Bromberg's involvement in the book before he was appointed by the court. Bromberg began working on the book, a multivolume treatise on securities law, with First Jersey attorney Louis D. Lowenfels about five years ago.

"First Jersey and the professor want to avoid even the most remote appearance of a conflict," Brennan said. Although Bromberg's authorship of the book was not at first seen to be a problem, Brennan said, Bromberg reevaluated his position after reporters raised questions about a possible conflict of interest. "None of us had really focused in on the fact that it might even in the remotest way have the potential to create the possible appearance of a conflict," Brennan said.

Sorkin said the SEC and First Jersey would attempt to agree on a possible replacement for Bromberg, and if they could not, each side would submit a list of names to the judge and let Pollack select one. Brennan said he hoped First Jersey could come up with a consultant acceptable to the SEC. "We certainly want the SEC to have good feelings about the consultant, just as they did about Professor Bromberg," he said.