A high school in Lismore has been forced to seal off a dozen classrooms following the discovery of asbestos.
The Department of Education says two classrooms at Richmond River High School were placed out of bounds on Monday and 10 more contaminated rooms have been discovered on Tuesday.
Students and parents were informed on Monday.
Traces of asbestos were found in the rooms’ window sills and a further 10 rooms with similar window sills have been placed off limits as a precaution, an Education Department spokesman said.
Remedial work has started and the school hopes some rooms will be fit for use by the end of the week.
Year 7 and 9 students are currently undergoing NAPLAN exams, which are not expected to be disrupted.