More than 100 year-13 Mt Albert Grammar students marched to their school today claiming they were banned from their last day to avoid pranks.

Photo: RNZ/ Katie Scotcher

In an email sent to parents last night, the Auckland school said instead of attending their final day, year-13 students have been granted study leave.

Principal Patrick Drumm said the decision wasn't made to avoid pranks.

However students disagree and stormed on to the school grounds in protest.

Year 13s at Mount Albert Grammar School were expecting to go to school for their final classes today.

But at the 11th hour they discovered this wouldn't happen.

"Yesterday we were called into assembly at 2:30pm and we were told that we have today off as study leave and that we're going to be treated as adults," year 13 student Hannah Zwalue said.

Ms Zwalue had originally organised a picnic for her classmates to celebrate their last day of class at a nearby park.

But that quickly turned into a protest.

More than 100 students marched on to the Mount Albert Grammar School grounds this afternoon - claiming their last day was cancelled to avoid pranks.

That upset many of her classmates, Ms Zwalue said.

"Lots of people were very upset, I know quite a few people were crying, there was a lot of anger as well. People are very mad about it," she said.

Celebrating the final day of high school was a rite of passage, Ms Zwalue said.

"Every single adult seems to remember their last day of school very fondly and they have very great memories of it and we don't have that at all," she said.

Fellow year-13 student Reuben Cato said the move shows the school did not trust its students.

"They're one minute 'we trust you guys, you're so great' and next minute saying 'by the way, we don't trust you in the slightest, we think you're going to be stupid," Mr Cato said.

Another student, Theodore Heeringa, was one of those who stormed on to the school grounds.

"They're just trying to...keep up the good image of the school at the cost of the student experience," Mr Heeringa said.

Mr Drumm was nowhere to be seen as the students flooded on to the grounds.

But he earlier said students weren't banned to avoid pranks.

"I wasn't aware of any pranks planned but certainly that may have been a possibility, but we've just sort of taken that out of the equation, sending a strong message that our primary concern for them is finishing the year strongly and positively," Mr Drumm said.

Today was not the 450 students' last day at school, Mr Drumm said.

"Their final day is actually on Monday, it always has been. They've also got their prizegiving on Monday afternoon here at school for them and their families and then we go on to the next major event which almost all of the Year 13's will be attending and that's their leavers on Monday night," Mr Drumm said.