(CNN) -- In the decade following the September 11, 2001, attacks, four CIA officers directly collaborated with the New York Police Department to expand NYPD's counterterrorism capabilities, according to a newly disclosed report.
The CIA inspector general's report -- completed in late 2011, but just declassified in response to a Freedom of Information Act lawsuit by The New York Times -- raises concerns about the relationship between the organizations.
The investigation found "irregular personnel practices" and "inadequate direction and control" by CIA managers "responsible for the relationship."
"As a consequence, the risk to the Agency (CIA) is considerable and multifaceted," said a memo from Inspector General David Buckley to David Petraeus, who was the CIA director at the time.
"While negative public perception is to be expected from the revelation of the agency's close and direct collaboration with any local domestic police department, a perception that the agency has exceeded its authorities diminishes the trust place in the organization."
CIA agents are prohibited from taking part in domestic spying and the report's release comes in the immediate aftermath of leaks by National Security Agency contractor Edward Snowden.
The investigation was launched after an Associated Press story that alleged "inappropriate CIA involvement in the activities of the New York Police Department," the inspector general's report said.
The AP reported that the NYPD Intelligence Division dispatched CIA-trained undercover officers into minority neighborhoods to gather intelligence on daily life in mosques, cafes, bars and bookstores.
It said New York police have used informers to monitor sermons during religious services and police officials keep tabs on clerics and gather intelligence on taxi cab drivers and food-cart vendors, who are often Muslim.
The New York Police Department blasted the report as "fictional," at the time.
A year ago, New Jersey Muslims filed a lawsuit against New York City, accusing police of using unconstitutional tactics to spy on them in the years after September 11.
The NYPD later said the surveillance never produced a lead that linked to a potential terrorist plot.
While the inspector general's report found no reason to order a full investigation into the relationship, it did note that the "risks ... were not fully considered."
NYPD Deputy Commissioner Paul Browne hailed the cooperation between the agencies.
"We're proud of our relationship with CIA and its training expertise, which is in part responsible for the fact that the 11 years since 9/11 and the anthrax attacks soon thereafter mark the first decade in the last six in which there hasn't been a single casualty of a terrorist attack in New York City," he said in a statement. "Not that the terrorists have stopped trying."