King's College, which attracted national attention over a student's alcohol-related death in May, has disciplined pupils for drinking liquor on a trip to Japan.

Senior students from the $20,000-a-year school in South Auckland were suspended for two days for drinking sake on a night out.

Headmaster Bradley Fenner said drinking on field trips was against the college's policy.

"On the final night of the trip the students were given some time to see the local sights in a place, somewhere in Tokyo. They went into an inn and sampled some sake," he said.

"There was no drunkenness but it was something that was outside our rules and we've dealt with them appropriately."

A concerned parent said at least nine students on the commerce and business studies trip had been suspended, but Mr Fenner wouldn't give the number or the age of those disciplined.

"We're disappointed with our students. But teenagers will make mistakes from time to time. There was no harm done.

"They were good students who made a poor decision. They've been dealt with, and that's the end of the matter."

The concerned parent said heads of house and others in leadership roles were involved.

Mr Fenner said the school holiday trip, to three Asian countries, was otherwise a successful educational tour.

King's has been in the spotlight this year over drinking issues.

In June, some parents controversially planned to organise an after-ball where their children could drink alcohol in controlled circumstances. It did not proceed.

The month before, student James Webster, 16, died after binge-drinking neat vodka at a party in Grey Lynn.

Mr Fenner said he did not think King's had a more acute drinking problem than other high schools. "It is something that is society-wide and an issue we need to be continually working on with young people."