Two of the three Year 10 South Otago High School pupils suspended last week after being caught using drugs at a school camp have returned to the classroom but the school is undecided on the fate of the other.
The board of trustees met on Tuesday night and agreed to immediately re-admit two pupils, with unspecified conditions.
The school would monitor their progress.
Principal Nick Simpson said it was "not making the progress we would like" with the third pupil, but declined to elaborate.
All three pupils are thought to be aged 14.
Four others, who were stood down after the incident, returned to school yesterday and today.
The pupils were attending the camp at the Tautuku Outdoor Education Centre in the Catlins.
