INSPECTORS are warning that industrial action by teachers is leaving them unable to reassure parents about the quality of children's education.
The Education and Training Inspectorate (ETI) has been unable to compete 161 inspection reports so far this year.
All main teaching unions withdrew cooperation with ETI as part of action short of strike.
They have rejected a pay offer that would see staff receive no across-the-board pay rise for 2015/16, and a 1 per cent cost of living uplift for 2016/17.
Guidance to teachers says that inspectors "should respect your right to take lawful industrial action and retreat from the room. Do not feel intimidated by the ETI - they are a visitor to your school and should behave accordingly".
Since the action began, inspectors have begun visits and reported as usual, but many reports have gaps and contain no overall inspection grade.
Between January and August this year, ETI visited hundreds of education and training providers and reports have been published online.
A total of 161 of these include the disclaimer "involving action short of strike".
The reports typically conclude that inspectors are "unable to assure parents/carers, the wider school community and stakeholders of the quality of education".
Among the work inspectors said they could not evaluate were learning outcomes for children, including those who require additional support with aspects of their learning.
In addition, ETI said it could not evaluate the quality of the curriculum at schools, the effectiveness of guidance and support in bringing about high quality individual learning experiences and the effectiveness and impact of planning, teaching, learning and assessment.
The schools for which reports were incomplete are now "high priority for future inspection with no further notice".
ETI said its focus is on ensuring that all pupils were getting a good education.
"The ETI inspect without fear or favour to promote improvement. Completing inspections in full, when they are scheduled, is in the best interests of the pupils and provides inspectors with a comprehensive picture of the school so that improvements can be made, where they are needed," a spokeswoman said.
"It is regrettable that due to action by the teaching unions, some schools have not been co-operating with the ETI.
"Our focus is on ensuring that all learners are getting a good education. This protracted period of action short of strike prevents ETI from highlighting where improvements are needed and in some cases urgent improvements are needed.
"A failure to implement these improvements may ultimately have a detrimental impact on the learner."
