A Canterbury teacher has been dismissed for sending inappropriate text messages to a student.

Ashburton College principal Grant McMillan said the teacher was stood down in late March after the messages came to school's attention.

He would not reveal the nature of the messages, but said they were "well outside the bounds of education".

Mr McMillan did not give details of the teacher or student involved.

An initial investigation was carried out within the college and the matter was referred to the board of trustees, he said.

"The end result of that was the board of trustees dismissed the teacher last week for serious misconduct," he told Radio New Zealand.

Police have not been notified, and the matter was now before the Teachers' Council.