Despite a legal mandate that gym classes be offered every school day, only 4% of New York City third-graders participate in daily physical education activities, a new report by the city’s public advocate finds.

The report, based on a survey of 100 randomly selected schools in the five boroughs, also concludes that only 12% of fourth-graders get the mandatory 120 minutes a week of physical education.

“Many schools are breaking the law,” Public Advocate Betsy Gotbaum said in a statement. “We must work to curb rising obesity rates and make sure exercise and physical wellness is a top priority.”

State regulations mandate that all public school students attend and participate in physical education, with a ladder of how often they are required to do so depending on age: once a day up to the third grade; three times a week for fourth- through sixth-graders, and twice a week one semester and three times a week the other for seventh- through 12th-graders.

Ms. Gotbaum’s report finds gaps in middle schools as well as the lower grades. A sample of 50 middle schools found that 69% violated state regulations and 48% had no athletic teams or sports program.

The city’s Department of Education says it has been pushing hard to reverse historical neglect in this area. It created for the first time an Office of Fitness and Health Education and appointed a director, Lori Rose Benson, who has been pushing physical education as a priority both inside the administration and inside schools, and who for her efforts last year was named top physical education administrator of the year by the National Association for Sport and Physical Education.

Two months later, the group awarded another honor to the New York City school system, making it the first district ever to be recognized.

Yet Ms. Gotbaum’s report adds to a growing chorus of critics suggesting that the Department of Education is not working hard enough.

Governor Spitzer addressed the issue in his State of the State address in January, saying state physical education standards are “widely ignored” and asking the comptroller, Thomas DiNapoli, whose office audits public schools, to handle oversight of the issue.

At a state Assembly hearing on physical education compliance earlier this year, the city comptroller, William Thompson Jr., said physical education is a major concern for parents.

He said lack of space is a big obstacle, citing Brooklyn’s District 15 as an example. “Many schools in the district were built without gyms, and there are currently no gyms at seven elementary schools in the district,” Mr. Thompson said.

Ms. Benson, the department’s health and physical education tsar, said she realizes many schools are not meeting state mandates, but that her mission is to reverse that. She has managed the creation for the first time of a core physical education curriculum; has lobbied the administration to make physical education part of the rubrics by which principals are graded, and has launched training programs to help schools increase their physical education, including a workshop titled “No Gym? No Problem,” in which schools learn techniques such as using classrooms for yoga and Pilates.

“There’s been increased concern about math and literacy scores and other core subject areas, and I think what we’re beginning to realize is that students’ health is a real core subject area,” she said. “We need to take that just as seriously as everything else.”

Ms. Benson said that one positive indication is already in: In 2003, only 75% of elementary schools had dedicated physical education teachers. Now, 90% of them do.