Parents and nannies should beware of unscrupulous, unethical, and unlawful nanny agencies, a City Council member said yesterday after releasing the findings from a more than two-month investigation into agency practices.

Investigators from the Committee on Oversight and Investigations found nearly half of the 37 investigated agencies were breaking state and city laws, a City Council member of Queens, Eric Gioia, said.

Eleven were operating without a license, eight charged improper fees to parents or nannies or both, and 10 did not list their license number on print advertisements, as required under a city rule, investigators found.

“Finding safe, secure, and reliable child care is one of the most difficult and stressful situations any new parent faces,” the committee’s chairman, Mr. Gioia, who became a father last summer when his daughter, Amelia, was born, said. “Our investigation reveals that outdated laws and lax enforcement mean that neither nannies nor parents are being served.”

Between January 25 and April 6, investigators posing as parents looking for a nanny for a 2-year-old child called 52 nanny agencies in the city. They asked about agency contracts, fees, and background checks on nannies. Staff members made another round of calls posing as nannies seeking employment.

Five of the agencies surveyed were charging an application or registration fee to nannies, and four required parents to pay a similar fee. Both practices violate state law.

Investigators found the agencies differed broadly in checking references for nannies. Ten agencies surveyed said they do not conduct any background checks on the nannies they hire, which is not required by law.

The Department of Consumer Affairs conducted a similar investigation in 1992 and found that 90% of nanny agencies surveyed were violating state and city laws.

The authors of “The Nanny Diaries,” Nicola Kraus and Emma McLaughlin, said they support the council’s investigation and are heartened by the attention to the difficulties facing nannies and parents.

“In our experience there is a lot of fear on both sides. There is a lot of distrust on both sides,” Ms. McLaughlin said, referring to the relationship between parents and nannies.

Several nanny agencies were contacted for this story, but none could be reached for comment yesterday.

Mr. Gioia said the Department of Consumer Affairs should increase its oversight and regulation of the nanny agency industry, especially because parents are increasingly seeking outside help to raise their children, he said.

“As part of the Department’s longstanding and aggressive approach to routing out deceptive business practices in employment agencies, we will review the Council’s recommendations and continue to expand efforts to educate both job seekers and employment agencies about their rights and responsibilities.” a spokeswoman for the Department of Consumer Affairs, Shira Krance, said in a statement.

Mr. Gioia also wants the city’s information hotline, 311, to record complaints about nanny agency abuses or violations, he said. When a 311 dispatcher receives a call about a nanny agency, the caller is sent a form that they must fill out and mail to the city.

In 2003, the council passed a law requiring agencies to give nannies and parents information about nannies’ rights and requiring parents to sign a document outlining a nanny’s specific job requirements.