Police are investigating sexual assault allegations made against a teacher at an Anglican all-boys school in Melbourne’s south-east.

The Brighton Grammar School teacher is being investigated over the alleged sexual assault, reported to have happened in Sandringham on August 9.

Victoria Police said a 19-year-old girl reported being sexually assaulted by a man known to her.

Bayside Sexual Offences and Child Abuse Investigation Team detectives are leading the investigation.

“Investigations into the incident remain ongoing,” police said.

Brighton Grammar headmaster Ross Featherston told the school community the secondary teacher had agreed to take leave.

In an email to parents on Tuesday, Featherston said the matters concerned the teacher’s work outside of school.

“To the best of our knowledge, no BGS (Brighton Grammar School) student is impacted,” he said.

When contacted by The Age, Featherston said the school did not wish to comment on the matter.