The New Haven Police Department may have added three assistant chiefs Wednesday, but aldermen are making it clear that they are the ones who will decide whether those additions will be permanent.

In testimony before the Finance Committee of the Board of Aldermen Thursday night, Police Chief Frank Limon and Chief Administrative Officer Robert Smuts ’01 said the promotion of three officers to empty assistant chief positions — bringing the number of assistant chiefs from one to four — was necessary for the management of the department. But a majority of aldermen opposed filling the vacancies last week, and several said Thursday that the Board of Aldermen, which must approve the next fiscal year’s police budget, may decide against permanent funding for all four positions.

“It’s definitely not a done deal,” Ward 9 Alderman Matt Smith ’98 said.

As a paramilitary organization, the police department needs all four assistant chiefs to promote internal discipline, Limon said. The hierarchy that comes with a strong management team makes also makes the department more effective, he added.

Ward 7 Alderwoman Frances “Bitsie” Clark agreed, citing her recollection of her husband’s time in the military.

“You don’t just eliminate a bunch of majors from the army, do you?” Clark said outside the Finance Committee meeting Thursday night.

The three assistant chief vacancies were created in the past year with the retirements of Assistant Chiefs Thomas Wheeler, Ariel Melendez and Stephanie Redding (wife of now-Assistant Chief Patrick Redding). Tobin Hensgen became the only assistant chief left at the department when Wheeler announced his retirement March 8.

Despite Limon’s request at a March 2 Board of Aldermen meeting to fill the vacancies, several aldermen have been skeptical of whether the department needs all four assistant chiefs.

Twenty aldermen signed a letter April 1 urging Mayor John DeStefano Jr. to postpone filling any assistant chief positions until aldermen could examine the department’s “supervisory needs.” New assistant chiefs should not be hired “simply because the positions happen to be budgeted and vacant,” the aldermen wrote.

When the assistant chiefs’ appointments were made, Ward 12 Alderman Gerald Antunes said he supported the promotions. But Thursday night, Antunes said he does not think the police department needs more than three assistant chiefs. Specifically, he said, it is unnecessary to have an assistant chief in charge of technology initiatives, the position currently held by Tobin Hensgen, whom Limon brought with him from the Chicago police force.

“We’re wasting $105,000 on an extra assistant chief that we could be using to make sure our children have a place to study,” Antunes said.

At their swearing-in ceremony, Mayor John DeStefano Jr. said the promotions of Capt. Patrick Redding, Lt. Petisia Adger and Lt. John Velleca would actually save the city money: While their new salaries are higher, as managers, they will not be paid overtime.

The elimination of one captain and two lieutenant positions from the department will also compensate for the cost of the promotions, Smuts said. The department is “slimming down its command structure” by not filling the three positions vacated by the promotions, Smuts said.

Clark said she hopes the savings from those cuts will be used to better fund the city’s libraries. Because of an 11 percent budget cut and layoffs of 12 library workers in February, libraries have had to cut hours throughout the city, with not a single library open on Saturdays except the main branch.

“When we close the libraries down, we’re throwing kids out onto the street,” said Clark, who added that she was convinced of the urgency of keeping libraries open on the weekends after attending a community meeting organized by Ward 19 Alderwoman Alfreda Edwards last week.

Libraries are important as safe, nurturing places for at-risk youth to go, said Clark, who is chairwoman of the Board of Aldermen’s Youth Services Committee. Ward 29 Alderman and Board President Carl Goldfield said aldermen are already in discussions about reallocating the money saved from the three position eliminations to the libraries.

But Smith emphasized that the Board of Aldermen, especially given a ballooning city budget gap, could not be expected to automatically put a stamp on the promotions in next year’s budget. Final authority rests with the Board of Aldermen, he said.

The Board of Aldermen must approve a city budget for fiscal year 2011-2012 before it begins July 1.