Teacher resigns amid student sex claims

A female teacher at an all-boys Catholic school in Sydney has resigned over reported inappropriate relationships with students.

Fairfax Media reports the St Aloysius' College teacher, who is understood to be aged in her late 20s, had sex last year with at least two Year 12 students, who were over 16-years-old.

The teacher's behaviour was exposed when a parent found out about a relationship with her son, the report states.

The Milsons Point school's rector Peter Hosking told Fairfax the teacher had left the school after an internal investigation into inappropriate conduct.

"The first was an investigation by the school and the findings have been reported to the NSW Police," he said.

"There have also been reports to the Ombudsman."