The New York State attorney general, Eric T. Schneiderman, announced on Wednesday that his office was opening an investigation into potential voting irregularities during the presidential primary on Tuesday, when New York City’s Board of Elections found itself besieged by complaints that it had dropped thousands of Democratic voters from the rolls in Brooklyn, among other issues.

Mr. Schneiderman’s office said it had received more than 1,000 complaints from voters across the state, dwarfing the roughly 150 reports it received for the 2012 general election. Many people said they had tried to vote, only to be told that they were not registered — the most common complaint, according to Mr. Schneiderman’s office. Among complaints from New York City, the largest chunk sprang from Brooklyn, where there were reports that the voter-information books in some polling places were missing multiple pages.

“By most accounts, voters cast their ballots smoothly and successfully,” Mr. Schneiderman said in a statement. “However, I am deeply troubled by the volume and consistency of voting irregularities.”

The board’s much-maligned Primary Day performance is also being audited by the office of Scott M. Stringer, the city comptroller, who on Wednesday released an online form for voters to submit information about their experiences.