A number of students from a Western Sydney selective high school have allegedly accessed a computer system using a teacher's login details.
The New South Wales Department of Education confirmed on Friday the Board of Studies, Teaching and Educational Standards (BOSTES) received an allegation about school assessment marks regarding students at Penrith High School.
"The school is looking into the matter and is working with BOSTES," a spokesperson for the department said.
"Any allegation that is made to BOSTES is taken seriously, and a comprehensive investigation is underway."
The Higher School Certificate (HSC) is the highest award in secondary education in the state, and to be eligible for the award, students must complete years 11 and 12, satisfy HSC course requirements, and sit for the statewide HSC examinations.
According to the department, the students will still undertake their HSC examinations at the school, which begin on October 12.
"BOSTES reminds students that there are severe penalties for cheating in the HSC," the spokesperson said.
"They may receive zero marks for a school assessment or zero marks for an exam, and potentially not receive the HSC."
Whilst Penrith High School has reportedly taken appropriate disciplinary action against the students, the department declined to comment on whether any of the students had successfully altered their marks within the computer system, but it did say that the school has assured BOSTES that the "correct and true marks" will be submitted.
The selective public school was ranked number 33 in the 2014 HSC High School rankings for the state, down four places from 2013.
"Students can be assured that stringent assessment and exam rules and procedures are applied by BOSTES to ensure the HSC's fairness and integrity.
"If the allegation is substantiated, BOSTES will act to ensure no student is disadvantaged, and the examination process remains fair."