By JENNIFER LEE

At a time when food stamp enrollment is soaring in the city and across the nation — to the point where one New Yorker out of five takes part in the federal nutrition program — advocates have continued to raise questions about New York City’s requirement that food stamp applicants be fingerprinted.

The advocates assert that the requirement — intended to help prevent fraud — deters some needy people from applying because they are put off by fingerprinting, which many consider intrusive. Betsy Gotbaum, the public advocate, has called the requirement “a very expensive failure.”

New York, Texas, California and Arizona, which together have more than a quarter of all food stamp recipients nationwide, all have the fingerprinting requirement. Studies by the Agriculture Department have found that the fingerprinting rules do not necessarily reduce error or fraud, and may reduce food stamp participation rates — a fact that the critics say means the requirement should be discarded.

At a Nov. 24 hearing held by the General Welfare Committee of the City Council, finger-imaging was repeatedly brought up in questioning and testimony.

Robert Doar, the commissioner of the city’s Human Resources Administration, argued that finger-imaging was a cost-effective way to catch fraud. In 2008, the screening cost the city $155,000 but caught 1,000 fraudulent cases, which the commissioner said potentially saved $2.8 million worth of misspent benefits. He added that over the last 10 years, the system had saved $27.8 million in actual or potential fraud. Food stamp enrollment has jumped by more than 288,000 in the last year, he said, demonstrating that applicants were not being deterred.

But at the hearing, Kevin W. Concannon, the federal Department of Agriculture’s undersecretary for food, nutrition and consumer services, who oversees the national food stamp program, appeared to undercut Mr. Doar’s reasoning.

Mr. Concannon said he would not recommend the finger-imaging requirement for any additional states, citing “concerns about the unintentional consequences.”

According to a transcript of the hearing, he noted that the states “that don’t use finger-imaging have no higher rates of fraud than New York has, and maybe there are other ways to ensure that people are not fraudulently receiving benefits.”

Over the years, many local officials have spoken out against the finger-imaging, including Christine C. Quinn, the City Council speaker; Bill de Blasio, who is chairman of the General Welfare Committee and was elected last month to succeed Ms. Gotbaum as the public advocate; and Representative Anthony D. Weiner, the Queens congressman who ran for mayor in 2005.

Federal law requires that an applicant’s eligibility for food stamps be determined within 30 days, or even as short as five days under an expedited process. New York’s compliance rate for both exceeds 93 percent, according to the Human Resources Administration.

That is not the case everywhere. In Texas, applicants are waiting months to go through the finger-imaging process, which the Obama administration has called unacceptable. According to a transcript provided after the hearing, Mr. Concannon said, “We have sat and I have sat in rooms with Texas officials and have told them that they should set aside finger-imaging because it is just one more step in a complicated, patient process that takes time but also results in deaths.”