CIVIC CENTER — More than two-thirds of Success Academy charter schoolswere under-enrolled last year and enrollment rates for four of them were so low that the schools should have been placed on probation, a collection of parents advocates charged on Wednesday.

Dozens of angry parents gathered at a press conference on the steps of Tweed Courthouse calling on the city Comptroller to investigate why charter schools were granted space despite low enrollment when their children’s public schools were packed.

“Over and over again, charter schools are given special treatments, they are given free space when public schools need it, it’s outrageous,” said Tess Vacin, a 42 year-old mother of two from Hamilton Heights.

Out of the 18 Success Academy Charter Schools that opened in 2013, 13 were 7.6 percent under-enrolled on average, and as of Oct. 31, 2013, Success Academy had 355 open seats, according to data culled by the parents.

Brooke Dunn Parker, one of the parent organizers, said enrollment data came from the  2013-2014 “Blue Book”, DOE’s annual report on schools capacity and enrollment rates, used to assess buildings’ utilization.

Additionally, Fort Greene, Crown Heights, Hell’s Kitchen and Union Square Success Academy Charter Schools — with under-enrollment rates ranging between 22 percent and 33 percent — failed to meet their projected enrollment targets, which put them in violation of their charter agreement and New York state law, parents charged.

The enrollment target data was found on charter school and SUNY websites.

SUNY, which is in charge of reviewing charter schools’ applications as well as overseeing and evaluating the operation of charter schools, allows for some latitude plus or minus 20 percent to deal with under-enrollment in the first year, a charter school source said.

Dunn Parker, a mother of three, two of which are enrolled in city schools, said it took her and a few other parents more than a year to find and compile the data.

“SUNY should have acted and should put these schools on probation immediately,” said Dunn Parker at the meeting. “They had this information in front of them.”

But a SUNY Charter Institute spokesman said that preliminary numbers indicate Success Academy schools are within the enrollment range approved in their charter contracts.

Success Academy Charter Schools also rejected this data, calling it “woefully out of date” and saying it did not reflect the current reality of charter schools in New York City.

“Enrollment numbers are targets that are dependent on space allocation, which leads to misunderstanding and confusion. This results in some enrollment issues in the first year, but not nearly the level referenced in this inaccurate and outdated report, ” said Success Academy spokesman Whit Clay.

Success Academy has received 16,000 applications for 3,000 open seats for the 2014 school year, Clay added.

When a charter school application is granted, enrollment numbers are set prior to the determination of where the school will actually be located. At that time, the schools do not know how many seats will be available, according to a charter school source.

The public school parents’ press conference came as the SUNY Board of Trustees’s Charter Schools committee granted 17 new charter schools in New York City on Wednesday.

Fourteen of the new charter schools will be run by Success Academy Charter Schools, which will open four schools in August 2015 and an additional 10 schools in September 2016, according to SUNY press release. The three other new charter schools will be part of the Achievement First Bushwick network with two charter schools opening in Brooklyn in 2015 and another one opening in August 2016.

“There are 32 kids in my daughter’s fifth grade class,” said Kemala Karmen, 52, whose 10-year old daughter attends Brooklyn New School. “I was at her school recently and I couldn’t find any free space, the school is at its contractual limit.”

Among other requests, parents asked the NYC Comptroller to conduct an independent audit on the enrollment, attribution, suspension and expulsion rates at all charter schools. They also asked for a moratorium on the authorization of any new, replicated or expanded charter schools until such audit had been completed.