Students at the elite Somerville House girls' school in South Brisbane have been disciplined in relation to a drug-related incident.

The students are believed to be in Year 9 at the Presbyterian and Methodist Schools Association-run school.

Principal Kim Kiepe confirmed no students were expelled, but a small number were involved in the prescription drug-related incident.

"The school takes all reports of alcohol, drug or substance use very seriously and has thoroughly investigated each matter in detail," Mrs Kiepe told The Courier-Mail.

"The consequences for each student involved in this incident were appropriate, according to the seriousness of their behaviour.

"When there are reasonable grounds to believe that a student on school property or at a school event or in school uniform is in possession of illegal drugs or implements associated with illegal drug use and/or manufacture, as principal, I am required to act in a manner that upholds the health, safety and wellbeing of all members of our school community," Mrs Kiepe said.

"To respect the privacy of those who are involved, we are unable to disclose any specific details."

Somerville House's school policy states the use, possession and supply of drugs and drug paraphernalia by students are strictly prohibited.

Originally published as Elite school disciplines girls over drug incident