A civil liberties campaigner says it "would be completely improper" if students at a Northland school have been filmed while using the toilet.
This would breach "the students' right to privacy", lawyer Michael Bott told the Herald.
His comments follow revelations that two surveillance cameras were fitted in the Year 9-11 girls' and boys' toilets at Tauraroa Area School, about 25km south of Whangarei, last week.
Principal Grant Burns said, in an email seen by the Herald, the cameras were mistakenly fixed inside the toilets rather than at their entrances where they would have overlooked a nearby area containing student lockers.
"I have already let a number of staff, parents and students know this. Steps have already been put in place to remedy this," he wrote.
A Privacy Commissioner spokesman did not wish to comment on the cameras at Tauraroa Area School but agreed a school's surveillance cameras should not "be collecting images of people half undressed sitting on a toilet".
However, schools might be able to fix cameras in toilets in areas where people were not getting undressed if they had "strong justification" to do so.
This may include cases where there was concern over sexual or physical assaults and vandalism.
However, Year 11 student Aart Lewis said his fellow students had felt "pretty disgusted because, in the boys' toilets, [the camera] looks straight onto the urinal".
"And the girls' toilets, they all get changed for netball and after school sports in those toilets," he said.
He said it was baffling how the mistake had occurred.
"Surely the people installing it would question if it was meant to go in the bathrooms or not because it is not really right," he said.
He felt the school was then slow to respond to student concerns.
While students quickly reported the cameras to teachers, Lewis did not hear the school make a public statement about what was being done to fix the situation until Friday.
Students had also kept covering the camera in the boys' toilet with paper, but this was removed at least three times by staff, he said.
He felt the situation should have been handled better, given the cameras were "pretty big news for a small school".
By Sunday, the school had posted a note on its website advising of the mistake.
"Please be aware that security cameras have been installed incorrectly near the main senior toilets," the statement said.
"These are going to be relocated as soon as possible. Thanks for your patience."
In a 2013 Privacy Commission case, a pub agreed to remove surveillance cameras from its toilets after a man complained they interfered with his privacy.
While the Commission agreed most cameras in the pub were "reasonable" measures to ensure safety, it found no clear purpose for the toilet camera.
"We considered that a camera placed in the men's toilet area was capturing highly sensitive information in an unreasonably intrusive manner," the Commission report said.
A source who claimed to be a Tauraroa Area School staff member told the Herald the cameras may have been installed to catch a potential vandal.
"To my knowledge there could have been some vandalism but no fights or serious incidents, like drugs."
The staff member said they only found out the cameras had been installed when students told them.
Later, "there was mention at [a] staff meeting and there have been signs up outside the school buildings, saying CCTV monitoring has been installed, I believe, over the holidays".
The staff member feared speaking out about the cameras.
"I know that if I complained that I will have a target on my back."
Tauraroa Area School runs classes for students from Year 1 through to Year 13.
Lewis said primary students were not allowed in the high school area and that the toilets where the cameras were installed were mainly used by students in Years 9-11 and sometimes by students in Years 7-8.