SALEM — The voices of classroom teachers have been secretly recorded by students who, in at least one instance, may have been following the orders of a parent, city officials said.

School Superintendent William Cameron raised the issue of hidden audio recordings at a School Committee meeting this week.

"We became aware of two instances in the last month, and it seemed to be highly unusual the first time and very troubling when it happened again," he said.

Cameron said there appears to be no connection between the two incidents.

Although the school boss declined to identify the schools or students, or say why the teachers were being recorded and if parents were involved, other city officials said one incident took place recently at an elementary school.

"I've heard, in at least one instance, of a parent encouraging a student to audio record the classroom while the teacher was instructing," said School Committee member Kevin Carr

Police Chief Paul Tucker, who said he was briefed on the issue but is not investigating it, gave a similar version of events.

"My understanding is it's very young children doing it possibly at the behest of parents," he said.

Joyce Harrington, president of the Salem Teachers Union, said she was informed of an incident last week at a grade school.

"What I was led to understand is that there was apparently a parent who went to the principal with some sort of a recording," she said. "... And after a few seconds, when the principal apparently understood what it was, he said, 'I think this is an invasion of privacy.' I don't know what he said ... (but it was) something to that effect."

Harrington stressed that she does not have direct knowledge of the facts, but spoke with a staff member at the school where the most recent incident allegedly took place.

Harrington also stressed that the issue, at this point, is not a union matter.

Cameron said he decided to make his concerns public because it is potentially a serious legal matter.

"I thought it was important to let people know by a public statement that this is a felony," he said.

Secretly recording someone without their consent is a crime in Massachusetts.

If a child was following the orders of a parent, the matter should be investigated by police, Carr said.

Tucker said he understands one or both incidents involve children in the "early elementary grades."

"At this point, it's best handled by the school department," he said.

The school department has concluded its investigation and taken "appropriate action," Cameron said. He declined to say what action was taken.

The superintendent said he raised the issue publicly to make sure this doesn't happen again.

"I want to let parents and students know this is prohibited, and I want teachers to understand we appreciate the seriousness of what happened in these two instances."

He said it is a "very serious matter for reasons having to do not only with the privacy of teachers but the civil rights of other students."

Cameron said it does not appear the tapes were made public.

"I want to make clear there is no evidence that these recordings were disseminated and there is no evidence that anything was done with the recordings," he said.

In addition to being illegal, the use of hidden recording devices could have a chilling effect on education, Carr said.

A classroom, he said, should be a "comfortable learning environment for students and teachers where the freedom of exchange can go back and forth without fear of some type of secret audio recording to be used at a later date."

With the advent of digital recorders, iPhones and other high-tech equipment, schools need to start talking with parents and students, according to School Committee member Janet Crane.

"I just think we have to talk more about the appropriate use of technology in public, including, and especially, the schools," she said.