Wellington school Scots College has confirmed it has received an allegation of improper behaviour by a non-teaching member of staff. The staff member denies the allegation.
Police have confirmed they received a report from a parent of a Scots College student regarding the allegation but found there was no criminal offending and said they would not be taking any further action.
"The staff member involved vehemently denies the allegation," Scots College Headmaster Graeme Yule said.
The college was treating the complaint with the utmost seriousness and Scots College had offered its full cooperation, Yule said.
Scots College Board chair Steve McJorrow said it was important complaints be taken seriously.
"Often people who experience and report abuse of any kind have their complaints dismissed immediately, or have their experiences diminished. This discourages people from coming forward.
"We must take these complaints seriously so that people can get the care and support they need," McJorrow said.
Scots College said it would not be making further comment.
Scots College is a day and boarding school with junior, middle and senior schools that teach students from years one to 13.