A multi-agency effort to improve the 911 system was plagued with management problems that drove up costs to $2.3 billion and delays, according to a review from city officials released Wednesday.

The de Blasio administration's chief investigator and City Comptroller Scott Stringer studied a 10-year-old initiative, known as the Emergency Communications Transformation Program, that was faulted for poor management, cumbersome oversight and contractors that could not deliver.

"[The program] has suffered from significant mismanagement, which at times was nothing short of governmental malpractice," said Department of Investigations Commissioner Mark Peters.

Stringer's report highlighted initiatives that were never completed that hamstrung the project, such as a creation of a computer-aided dispatch system and a backup center to house the NYPD's 911 facilities.

Recommendations in the city's report could get major parts of the program completed in 2016 and the entire project fully finished in 2017, the mayor's office said.

Mayor Bill de Blasio said in a statement that the program can be salvaged by nixing consultants and improving communications between agencies.

"These are the reforms that will allow the ECTP to deliver on its promise to the people of New York -- a state-of-the-art system that can answer the call when New Yorkers are in need," he said.