The attitude of teachers towards the General Teaching Council for Wales is worsening because of the row over registration fees, according to a union.
Chris Keates, general secretary of the NASUWT, said at best teachers are indifferent to the GTCW, and at worst consider the regulatory body "a waste of time".
Her comments came as the union delivered giant postcards to the GTCW and the Assembly government last week, representing almost 5,000 postcards sent in by teachers across Wales protesting at the increase in the body's annual compulsory registration fee. The council blamed the 37 per cent fee increase - from amp;#163;33 to amp;#163;45 - on a rise in professional conduct cases.
Teachers in England have their amp;#163;33 fully reimbursed, and the Assembly government has been labelled "petty" for refusing to reimburse the amp;#163;12 rise, which Welsh teachers now have to pay.
Ms Keates said: "Is it any wonder that teachers are angry and that the response to the NASUWT postcard protest campaign has been so high?
"Teachers should not be penalised for working in Wales."
Rex Phillips, NASUWT Cymru organiser, said the "unfair and unjust" rise amounted to a tax on Welsh teachers worth amp;#163;354,720 a year, and called on the Assembly government to provide local authorities with extra cash to reimburse staff.
But an Assembly government spokeswoman said such a move would "reduce the GTCW's independence as a professional body".
She said the rise was based on a sound business case and would allow the council to continue to fulfil its statutory functions.
Unions and teachers' leaders have expressed concern over the growth in the GTCW's regulatory role amid accusations that it has become too heavy-handed.
Earlier this year, Welsh-medium teaching union UCAC said teachers increasingly see the council as a body that impeaches teachers, not one that protects them. But Gary Brace, GTCW chief executive, said the profession across Wales benefited significantly from the judgements reached in professional misconduct or incompetence cases.
He called the fee increase "absolutely necessary" for the GTCW to remain financially sound.
Meanwhile, the NASUWT criticised the Assembly government in an end-of-term style report. Ms Keates said teachers in Wales are treated less favourably than their colleagues in the rest of the UK.
She said: "It's not a case of could do better. It's a case of couldn't do any worse."
A government spokeswoman called the report "misleading".