Drugs found at Geelong Grammar campus

Drugs have been found in a search of boarding houses at Australia's most expensive private school while the students were back home for a weekend break.

Geelong Grammar students raised concerns about illicit drug use at the senior school's boarding house in Corio, prompting "comprehensive searches" on August 17 to 19.

The school charges almost $40,000-a-year in fees and once taught Rupert Murdoch, Prince Charles and Portia De Rossi, while Boris Johnson spent a year as a student adviser.

Principal Rebecca Cody spoke to the year 7 to 12 students on August 31 before an email was sent to parents about the school's "proactive measures" to respond to the illegal drug-use.

"As a result of these searches the school is better placed to support a handful of senior students and their families," Head of Corio campus Steven Church wrote to parents.

The school has not reported the matter to police, but will talk to students and parents about drug education.

"Education is a continuous process and we must always embrace teachable moments," Mr Church said in the email.