Mr Dempster added: "It's not a pleasant thing to have to deal with for any side. It's the headteacher who will have to start the proceedings. But as part of their professional role it is a nettle they need to grasp."
* Bill McGregor, general secretary of the Headteachers' Association of Scotland, said systems were already in place for new recruits. "The area of concern is the person who has been in post and has not cracked it at all.
We are talking about a very small, persistent hard core who are frankly quite appalling and should not be there at all," Mr McGregor said.
"It's not fair to say headteachers are ignoring the problem, although some may be. The great majority of our members are saying they have tried everything but local authorities will not bite the bullet and take the final step."