SYDNEY, Aug 8 - Practice papers for the upcoming HSC physics trial were stolen from a cupboard at the prestigious Scots College in Sydney's east between Monday night and Tuesday morning.

Police are working with the school to identify those responsible, a police spokeswoman said.

As a result of the theft, the Scots College has cancelled some of its trial HSC exams, a Catholic Secondary Schools Association spokesman told Fairfax Media.

"Our understanding is that Scots College will not be sitting any of the CSSA exams that were kept in that cupboard," the spokesman said.

"CSSA doesn't believe the exams have been compromised by this incident but we are monitoring the situation and if we receive information that changes our view, we will notify schools immediately."

There are strict protocols around the storage of CSSA papers which include storing them in a secure location.

A parent who contacted Fairfax Media said Year 12 students at the school were demanding that the boys involved be expelled from the school.