The once-classified inspector general's review, completed by the agency's inspector general in December 2011, found that the four CIA analysts were assigned at various times to "provide direct assistance" to local police, The New York Times reported Wednesday.
The report also raised concerns about the relationship between the two organizations.
One officer who helped conduct surveillance operations in the United States said he believed there were "no limitations" on his activities because he was on an unpaid leave of absence and exempt from the prohibition against domestic spying by the CIA, the report said.
Another embedded analyst who was on the spy agency's payroll said he was given "unfiltered" police reports that included information unrelated to foreign intelligence, the inspector general's report said.
CIA Inspector General David Buckley found the agency-NYPD collaboration was rife with "irregular personnel practices," lacked "formal documentation in some important instances," and agency supervisors exercised "inadequate direction and control."
The executive summary was declassified in response to a Freedom of Information Act lawsuit filed by the Electronic Privacy Information Center, a non-profit, civil liberties group, which provided it to The New York Times.
"The CIA is not permitted to engage in domestic surveillance," said Ginger McCall, the director of the group's Open Government Project. "Despite the assurances of the CIA's press office, the activities documented in this report cross the line and highlight the need for more oversight."
CIA spokesman Dean Boyd said Buckley found no violations or evidence that the agency's support to the Police Department constituted "domestic spying."
The department has slapped with lawsuits alleging unconstitutional surveillance of Muslim communities and mosques in New Jersey and New York.
Police spokesman Paul J. Browne said the lawsuits were meritless and that Buckley's report found nothing illegal. He said the last embedded CIA official left in 2012.
"We're proud of our relationship with CIA and its training," Browne said, saying it was partly responsible for the absence of casualties from a terror attack in New York since Sept. 11, as well as from anthrax attacks.
Terrorists, he said, "keep coming and we keep pushing back."