A New Jersey teacher has been arrested after a recording device was found inside staff toilets at the primary school where he worked.

Christopher Esnes, 40, was arrested on suspicion of placing an audio-video recording device inside a bathroom at Littleton School in Parsippany, New Jersey.

Police said the device was found inside an adult-designated bathroom by a school worker. Esnes was charged with invasion of privacy.

ABC 7 News said that police were not sure how long the device had been recording the toilet area.

The school district authorities said Esnes had been teaching at the school for 16 years but had now been suspended and banned.

No footage of children had been discovered on the camera, added police.

In a letter to parents Parsippany-Troy Hills School District interim superintendent, Lee Seitz, assured them that students were never at risk.

"Students do not utilise this restroom and we do not have any information that student privacy was compromised in any manner," Seitz said.

Liz Cordasco told television reporters that the arrest had come as a shock. She said: "He was a great hands-on teacher who knew all the students' names."