More than 20 Wellington High School students have been disciplined after using drugs and alcohol on a school ski trip.

For the past 10 days school staff have been questioning 60 students about drinking alcohol and smoking cannabis while on a school camp to Whakapapa skifield last month.

Yesterday, acting principal Dominic Killalea said 25 teenagers, ranging from year 10 to 13, were this week asked not to return to school for three days.

The students were not stood down but were undergoing restorative justice, though suspensions were possible, he said.

They would be called individually to a conference to discuss the incident and further discipline.

"I don't want a kid that smoked dope to think they're a terrible person. I want them to be a better person."

With school exams looming in two weeks it was a "serious time of year to have kids out of school".

"I reckon [Wednesday] was just about the worst day of my teaching career."

Police youth aid officers would be taking part in the restorative meetings and for those students who supplied the cannabis, suspensions were a possibility, Mr Killalea said.

"Some kids happened to be with a group of students and felt pressured to have a puff of a smoke or a sip of a drink.

"That's different to someone who brings something along with the intention of supplying it to others."

There were 101 students from the co-educational state school, accompanied by staff and parents, on the ski trip for three and a half days from August 20 to 23.

He would not reveal details of how the students were caught.

The Ministry of Education was alerted that the decile 9 school was dealing with "an incident involving students" and deputy secretary Katrina Casey said she was confident it would be handled appropriately.

Restorative justice meetings were relatively new to New Zealand secondary schools and other than Tawa College Mr Killalea said he did not know of other Wellington colleges using the system.

He hoped the conference would be the end of it for the students and that they would realise how much they had let the school down.

"Parents have a perception of their kids and for some their whole world has fallen apart.

"They're upset with their kid and they get upset with us," he said.

"I don't like what's going on but kids make mistakes and we have to deal with that."

The annual ski trip had never had issues with drugs and alcohol.

In the Wellington region last year 96 students were stood down for drugs and 37 students were suspended, which includes exclusions and expulsions.

Nationally 1185 students were stood down and 797 were suspended last year.