The Otago Daily Times has learnt the fire alarm was used to gather pupils on the tennis courts with their bags and, after a roll call, they were sent to an assembly while a detector dog sniffed their bags.
Parents spoken to confirmed nobody was allowed to leave during the search and owners of any bags identified were called out and were still being questioned when other pupils left the assembly. No drugs were found.
Some teachers contested the way the search was conducted, but were ignored.
The school says the detector dog exercise was ''conducted with the best intentions'' and did not involve personal searches of pupils or staff, but it will review the way it was carried out.
The ODT investigated after an email complaint to the newspaper about the way the search at Waitaki Boys' was conducted.
The newspaper checked the way the search was done against the ministry guidelines and identified breaches in areas ranging from blanket searches not being allowed, to a prohibition on using a detector dog on pupils' property.
Responding to questions sent to Waitaki Boys', commissioner Nicola Hornsey said her understanding was ''the dog search exercise was a Safer Waitaki initiative'' and staff were not involved.
The Safer Waitaki Community Council no longer exists.
But Derek Beveridge, who was associated with the council in the past, said that, in a private capacity, he arranged funding to pay for the detector dog to visit St Kevin's College and Waitaki Boys' High School, as part of having a safer community for young people.
It was up to the schools how the dog was used and to manage the process, he said.
St Kevin's deputy principal Kerry Ryan said the school had initiated the dog's visit and, with the funding obtained, was able to offer it to other schools.
''It's [a dog] not cheap. It can be very expensive, so it was great to get enough funding to be able to offer it to other schools.
''What we wanted was basically a familiarisation trip for the [detector dog] contractor. We have 50 acres of ground here and we wanted to make sure he was familiar with the ground, in case we ever needed him,'' Mr Ryan said.
Mr Ryan was aware of the guidelines and ensured they were followed, he said.
The school was told at assembly the day before about the detector dog and it was used only on school property, not pupils' property.
The St Kevin's exercise was done during normal school hours, when pupils were attending classes or moving around the grounds.
In a statement, Ms Hornsey did not comment on whether the detector dog was used on pupils' bags nor how the search was run.
Nor did she comment on whether it was a fire drill, pupils gathered en masse with bags were sent to an assembly and bags were then sniffed by the detector dog.
She said if pupils or parents had concerns about the process followed they were welcome to contact the school.
The ODT spoke to three parents of boys at the school who confirmed the basics of what was in the email, and added further information from their sons.
