Rotorua's only state-integrated high school wants to expand, but there are fears that would be detrimental to other schools in the city.
John Paul College has a cap on the number of students it can enrol but principal Patrick Walsh wants this increased.
Mr Walsh said increasing the roll would not affect other Rotorua schools as the extra students "would likely not be coming from the Rotorua region".
"Many of the families applying to attend John Paul College are not from Rotorua, so, if they can't get accepted by us, they will not likely send their children to another school in the area.
"The Ministry [of Education] has put a 1100-student cap on our roll, despite our school being able to accommodate 1200 students, because they say the extra 100 students would adversely affect the other schools in the area."
Mr Walsh said that would not be the case, and disallowing the increase would be "bad for Rotorua".
"It comes down to parental choice and people get very annoyed when we cannot accept their child and, as a result, send them to a school outside the district."
John Paul College had to close its enrolment period in August after reaching its maximum quota for 2015. Its current roll sits at 1126 students from Year 7 to Year 13.
As of 2013, Rotorua Girls' High's roll sits at 620 students, Rotorua Boys' High at 752, Western Heights High at 1513 and Rotorua Lakes High at 662 students.
Ministry of Education statistics show Rotorua Lakes High and Western Heights High have also had increasing numbers since 2009.
Rotorua Lakes High has jumped from 560 to 662 students in the past five years, and Western Heights High from 1463 to 1513.
However, Rotorua Girls' High's roll has decreased by nearly 300 students, and Rotorua Boys' High by just over 100 students, in the past five years.
Rotorua Girls' High School principal Ally Gibbons said increasing the cap at John Paul College could impact her school roll.
"It may only be 100 extra students to John Paul College but that could mean 100 fewer students for Rotorua Girls' High, taking our roll from 600 to 500.
"When I was working at Rotorua Girls' High School in 1999, the roll was at 1200. When I came back at the start of this year, the roll was almost half that. John Paul College says their cap should be increased because they have capacity to take 1200 students but so do we, and I would love to see our roll increase again."
State-integrated schools are merged into the state school system, while retaining their special character. John Paul College was integrated in 1986 as a Catholic school.
Ministry of Education head of sector enablement and support Katrina Casey said unlike state schools, state-integrated schools were subject to maximum rolls.
"These maximums are agreed by the school proprietor and the Crown. Maximum rolls are always set in the context of the wider school network in the area."
Ms Casey said John Paul College's cap had been increased several times since 1986, most recently in 2009 when it was set at 1100.
She said, in 2012, the school applied to increase that to 1200 but was declined.
"This request was declined because there has not been any population growth in the area and the school network has sufficiently funded places for all students in the area."
She said the ministry had recently met with John Paul College to discuss concerns about their roll numbers.
Statistics for the projected underlying population age 13 to 17 in Rotorua, released by Statistics New Zealand, show a trend of slight decline in the secondary student population in the district over the next two decades.
Western Heights High principal Violet Pelham did not respond to the Rotorua Daily Post's requests for comment on her school's increasing roll.