Some of the worst examples of inept teaching practice in Wales may never be heard in public, it has been sensationally claimed.
Hayden Llewellyn, deputy chief executive of the General Teaching Council for Wales, said serious cases of incompetency by teachers may never reach the professional standards watchdog.
Speaking at the annual conference of the Association of School and College Leaders (ASCL) Cymru last week, Mr Llewellyn said that some cases may be dealt with behind closed doors by local authorities.
His admission means there could be incompetent teachers being recycled in Wales's schools because their records are unblemished.
And leading figures in the education fraternity are concerned that some teachers "who should never be in the classroom" are being paid off quietly by local authorities, only to re-emerge in other schools.
One source said: "I know of at least one case where this has happened, but how many are out there?"
Just two cases of incompetency have reached the GTCW over the past six years. One is still on-going.
Martin Reynish, an English teacher at Bryn Celynnog Comprehensive in Beddau, near Pontypridd, for over 20 years, is alleged to have let pupils set off fire crackers, use mobile phones, listen to MP3 players and play game consoles during lessons. More than 50 allegations were made of apparent inept teaching practice. But evidence in his support was given at an earlier hearing.
David Evans, NUT Cymru secretary, questioned why the school carried on raising Mr Reynish's pay based on good performance - and gave him a reference - if he was incompetent. In England there have been 12 such cases heard by the GTC since January.
Mr Llewellyn said either a school or LA can refer extreme cases of teacher incompetence, something not always known by school heads.
Mal Davies, head of Willows High in Cardiff and chair of the GTCW, said referral was a tricky area. But he denied teachers were being employed in other schools: "We would not be benefiting anyone if we passed on duff staff."
Mr Davies said the GTCW put in place clear procedures for referral, but some LEAs may have difficulty finding time to deal with it.
"Before the GTCW and Wales-wide incompetency procedures existed, LEAs and schools tended simply to remove poor-quality teachers from their 'patch'. This inevitably led to such teachers being recycled through the system.
"The responsibility lies firmly with employers to refer cases."