A 28-year-old woman who worked as an occasional supply teacher is facing charges after being accused of having a sexual relationship with a teenage student.

York regional police say they began investigating late last month after receiving information about a teacher who is alleged to have been involved in a sexual relationship with a male student between October and December of last year.

Police say the supply teacher has been working with the York Catholic District School Board since 2014.

In a statement provided to CTV News Toronto, a YCDSB spokesperson confirmed that the teacher in question was “immediately removed from her teaching assignment” when the allegations came to light and is “currently on leave.”

“These allegations are certainly upsetting for YCDSB. We take very seriously our responsibility to ensure a safe and respectful working and learning environment for all our staff and students,” board spokesperson Sonia Gallo wrote in the statement.

“These are serious charges and we are always very concerned by any circumstances in which students are at risk and there have been allegations against a staff member.”

Gallo added that the board is cooperating with police in their investigation. She said counsellors would be on hand at the unidentified school to provide support to “staff and students with concerns… for as long as needed.”

Marianna Riossi, 28, from Vaughan has been charged with three counts of sexual assault and three counts of sexual exploitation.

She is scheduled to make a court appearance in Newmarket on March 6.

None of the charges have been proven in court.

Investigators say they want to ensure there are no further victims and are asking anyone with information to come forward.

- With files from The Canadian Press and CTV Toronto