A Canberra Grammar School student was allegedly abused by a senior school staff member in the early 2000s.

The private boy school's head Justin Garrick said the student and the teacher no longer attended the school, and no details of the incident have been released because legal proceedings were underway.

"Please know that if any of our students, former students, families or staff have any concerns about this or any other matter, we stand by to provide support," the statement to parents read.

"In any such cases, the school will, as it has in this instance, inform and collaborate willingly with authorities.

"We will also strive always to act with the highest care for the wellbeing our students, former students and their families."

Mr Garrick said the incident was "a reminder to encourage all of our children to be vigilant, to understand their rights to privacy and to physical and emotional respect, and to be confident in raising any matters that worry them with their parents or teachers".

In June last year the school advised that another teacher had been charged with using a carriage service to transmit indecent material to a 13-year-old girl in New South Wales.