Welsh schools could face a wave of "major industrial relations problems" due to controversial new professional standards for heads and teachers, a teaching union has warned.
The NASUWT says it is "gravely concerned" at the Welsh Government's proposals, which it claims could lead to "punitive monitoring regimes" in which teachers are observed on the "pretence" of raising classroom standards.
The Government says the existing arrangements for school staff do not support current educational priorities, such as improving literacy and numeracy, and are not widely used as part of daily practice in schools. It has consulted on reformed standards.
But earlier this month the General Teaching Council for Wales condemned the proposed new leadership standards as "not fit for purpose", and headteacher unions NAHT Cymru and ASCL Cymru said they also had concerns.
Now, in a letter seen by TES Cymru, the NASUWT has launched a scathing attack on the proposals, which it says are "poorly constructed" and "unacceptable".
"The NASUWT is gravely concerned that the tone and thrust of the consultation and guidance documents present a vehicle for the introduction of punitive monitoring regimes that will seek to observe and scrutinise the work of the school workforce on the pretence that this will somehow raise standards," the letter says.
The union accuses the Government of failing to enter into "constructive and meaningful negotiations" over its proposals, and says it will defend its members from any changes that will have a "detrimental effect".
It is particularly concerned over the proposed Practising Teachers Standards, and accuses the Government of trying to introduce a "tick-list" of requirements that teachers must meet in their day-to-day practice.
In a letter responding to some of the NASUWT's concerns, a senior Government official says the standards will only form a "backdrop" to teacher appraisals.
"It is important that teachers meet the standard at the end of their induction period and continue to meet them to demonstrate that they are teaching effectively. We do not intend that this should become a bureaucratic process of evidencing that they meet each standard on a daily basis."
However, the NASUWT says it will "vigorously" resist any attempts to use the standards as a checklist to assess teacher performance.
It also accuses the exercise of being a "cynical attempt to divert attention away from the underfunding of the education system", and suggests it could constitute a "first step" in an "assault" on teachers' pay and conditions.
A Welsh Government spokeswoman said: "The consultation on the professional standards has now closed and we will consider all comments and contributions before making a decision.
"We are committed to working with stakeholders to draft guidance on changes to the professional standards and their use in performance management to ensure these changes provide more effective support for teachers and so improve learner outcomes."