The inspection system is facing a mauling by the three largest teacher unions at their annual conferences over Easter, with the spectre of a national boycott hanging over Office for Standards in Education inspections.

All three classroom teachers’ unions will hear motions calling for OFSTED’s abolition, and resentment about inspection is expected to be the most inflammatory issue at the conferences, dominating debate in the same way that class size did last year.

Anger is focusing on the new confidential reports by inspectors to heads on good or poor teachers, due to be introduced next term. The reports are widely seen by classroom teachers as an attempt to weed out “poor” teachers as part of chief inspector Chris Woodhead’s high-profile drive against the 15,000 incompetent teachers he alleges there are in schools.

The National Association of Schoolmasters Union of Women Teachers’ conference will hear six motions about OFSTED. One, which is supported by the executive, calls on members to “resist” the confidential reports. The executive also supports a call for union guidelines for members on how to challenge inspection by “inappropriately qualified” inspectors.

Other motions, not supported by the leadership, demand the immediate resignation of Mr Woodhead and condemn OFSTED’s “blatant entry into the political arena”.

NASUWT leader Nigel de Gruchy said this week that there would certainly be calls for a ballot on boycotts of inspections at the Glasgow conference after Easter. The executive would support this in “case by case disputes” at individual schools, he said, but would urge caution on calls for national action.

“But if, when OFSTED begins the new system on April 1, thousands of cases turn up of teachers being singled out, then it would become a national situation, ” he warned. The issue, he said, “has caused a massive amount of anger . . . no other professional group is singled out in this way; it’s very demoralising and demotivating.” He said that OFSTED’s argument that the reports were intended merely to complement existing appraisal was nonsense, and that any head who did not already know which members of staff were performing badly should not be doing the job.

Asked to speculate on what inspection boycotts or “non-compliance” would involve, Mr de Gruchy said it could mean teachers refusing to let inspectors into classrooms, refusing to talk to them and refusing to teach in front of them.

Commenting on the boycott threat, education minister Robin Squire said he thought it was unlikely to happen, but declined to elaborate on what the department would do if it did: “It is not for me to throw fuel on the flames - if there is indeed to be a fire.”

Chris Woodhead would not comment directly on the boycott threat, but he insisted that the reports merely formalised what was already happening during inspections. “Headteachers very much want the maximum possible information from inspecting teachers in schools,” he said, adding that “classroom teachers are fed up with carrying colleagues who should not be in the job”. Confidential reports will be triggered when a teacher is judged to fall into grades 1 and 2, or 6 and 7. OFSTED originally proposed 1 and 7 only.

The National Union of Teachers, which meets in Cardiff, plans to debate a motion calling for the end of OFSTED, instead establishing a system based upon self-evaluation by schools, the reincarnation of HMI and the statutory duty of local authorities to support and advise schools.

One amendment, which will not be supported by the leadership, is one from the London borough of Hackney - still smarting from the closure of Hackney Downs - which calls for a ballot for non-cooperation with OFSTED and the abolition of education associations.

Delegates, who fear the motion may be squeezed out because of lack of time, will press for a suspension of standing orders to ensure inspection is discussed.

At its Torquay conference, the Association of Teachers and Lecturers, which meets on Monday, will also hear a motion calling for the abolition of OFSTED. The assembly will be asked to deplore OFSTED’s increasing politicisation, and the use of inspection as a political weapon.

The ATL’s agenda this year reflects a profession which is feeling increasingly vulnerable. Motions calling for greater security in schools were composed before the Dunblane tragedy. And other issues given high priority on the agenda are harassment of teachers and threatening behaviour from pupils, colleagues and other adults. The union’s executive council will be asked to take a more pro-active role in tackling bullying and intimidation of teachers. Conference will also discuss the growing number of “unfounded and often malicious” accusations made by pupils against teachers.

The NASUWT is also to debate motions on accidents at schooland “bullying employment and management practices”. Delegates will also be asked to observe a minute’s silence for the children of Dunblane.