A parent group put in place to advise the city’s schools chancellor, Joel Klein, on high school policies is asking the city to put the brakes on opening any additional small schools.

Since taking the helm of the city’s education system, Mr. Klein has created about 180 new schools, an essential part of his plan to boost high school graduation rates.

In a letter sent to the schools investigator, Richard Condon, the group accused the Department of Education of denying enrollment to special needs students at these schools. The 11-member panel, the Citywide Council on High Schools, also passed a resolution last week claiming that the new schools and the closure of a number of large schools were leading to overcrowding at the remaining high schools.

It is asking the department to “substantially delay the implementation of new small high schools” until issues surrounding the enrollment process and the “negative impact” on other schools are addressed.

“The council was created by the chancellor’s regulations to advise the chancellor on high school policies, and the council has never been asked its opinion,” a parent on the council, David Bloomfield, said about the small high schools. He represents Region 10, which covers the Upper West Side, Harlem, and Washington Heights. The council, which also includes one high school senior, voted 7-0 in favor of the resolution and the letter.

In an attempt to address to the city’s four-year high school graduation rate, which hovers around 50%, Mr. Klein started dismantling some of he city’s largest high schools and opening smaller schools with emphasis on subjects such as civil rights and sports management.

Last month, Mayor Bloomberg announced that 36 more small schools would open in September. They will eventually enroll between 300 and 600 students each.

“These small schools have been a key part of our success in closing the intolerable achievement gap between races and ethnicities,” he said at J.H.S. 50 in Williamsburg, Brooklyn, which will house the Academy for Young Writers starting in September.

The Department of Education also said students who attended small schools had attendance rates eight percentage points higher than the city average and were more likely to be promoted to 10th grade from ninth grade.

Mr. Bloomfield claimed the numbers for small schools were higher in part because there are fewer special needs students.

About 50,000 students will be enrolled in the city’s new small schools by September, according to the Department of Education.

A spokeswoman for the department, Kelly Devers, said that all students have access to the new small schools.

“The new small schools are deliberately intended to create high-quality options in the city’s most underserved neighborhoods,” Ms. Devers said. “The goal is for these schools to serve all the kids in their communities. At the latest, by the third year, they should be able to serve any student that wants to go there.”

She said that because new small schools open with only five to six teachers and a limited budget for their first year, they are not often able to offer services for special needs students in their early years.

Special education students comprise 8.1% of the ninth-grade class at the new schools compared to 11.8% citywide, Ms. Devers said.

“There’s no reason why you can have a school open up and exclude a particular kind of student … because they are too much in need,” a member of the Citywide Council on Special Education, Ellen McHugh, said. Her son is deaf and is a graduate of the city’s public schools.

The council was put in place to advise the schools chancellor after the dismantling of the old Board of Education. The members are drafting a resolution about the new small schools that they intend to send to Mr. Klein. They also are sending a letter to the schools investigator accusing the Department of Education of violating special needs students’ civil rights.