A teacher at a large south-west Sydney Catholic high school has been charged with sexually assaulting one of his students.

Police will allege Roj Dalisay, 28, sexually assaulted a student at Mount Carmel Catholic College in Varroville, near Campbelltown, between 2020 and 2021.

Police began investigating in July 2023 when the Catholic Education Office became aware of the alleged incident and made a report to local police.

Dalisay worked as a maths teacher on a temporary contract, which was renewed in 2021. A spokesperson for the Catholic Education Diocese of Wollongong said Dalisay was stood down from his position after the allegations were made in 2023.

Dalisay was arrested at Auburn police station on Tuesday and charged with three counts of the aggravated sexual assault of a victim under his authority and one count of aggravated sexual touching of another person.

“After the CEO [Catholic Education Office] was notified by the college of the employee’s alleged actions, we implemented our established procedures. This involved reporting to NSW Police and notifying the Office of the Children’s Guardian,” the spokesperson for the local diocese said.

“The CEO and Mount Carmel Catholic College have been assisting police with their investigations – including by co-ordinating the provision of support, the standing down of the employee, and other actions taken by the college in relation to this matter – and will continue to do so.”

Dalisay on Wednesday faced Burwood Local Court, where he was granted bail.

The prosecution had opposed the granting of bail, citing risks of failing to appear at court, endangering the safety of the victim and interfering with witnesses.