Philip Banks III, the highest ranking black member of the NYPD, is quitting his job as chief of department and resigning from the force on the eve of a promotion, according to a high-ranked law enforcement official.

News that Banks, a 28-year veteran who was set to become first deputy commissioner on Monday, resigned stunned many on the 40,000 member force. Banks was also the highest uniformed official on the NYPD.

"I am crying," said the law enforcement official who asked for anonymity. "He is the best . . . thing in this department."

A spokesman for the NYPD couldn't confirm the report of Banks' resignation, first reported on NY1 on Friday morning. Neither Banks nor police spokesman Stephen Davis could immediately be reached for comment.

The law enforcement official, who didn't want to be named, indicated that Banks was unhappy with the fact that he was being bounced out of his chief of department job and made first deputy commissioner under commissioner William Bratton.

The loss of Banks, who was promoted to chief of department late last year, would undo some of Bratton's plans to reorganize the high levels of the NYPD announced earlier this week. As part of that reshuffle chief of patrol James P. O'Neill was to take over from Banks as chief of department.

"My God that is a shock," said police historian Thomas Reppetto. "I look forward to hearing the explanation for all this. Banks was clearly the heir apparent to the police commissioner job," Reppetto said.