Absence levels among teachers at a prominent Belfast primary school shot up to four times the Northern Ireland average, it has emerged.
Teachers at St John the Baptist PS, which inspectors awarded the second lowest performance grade of "inadequate", missed an average of 32 days in a single year.
Serious issues relating to leadership and management, accommodation and health and safety have been highlighted in a new report.
The school in west Belfast is now in the formal intervention process, during which it must work to address problems.
However, the Irish National Teachers' Organisation (INTO) said it had major issues with the inspection report, claiming that staff were being penalised for historical matters beyond their control.
Almost all teaching observed was "good or better" while performance data revealed that almost every pupil made good progress in English and maths in line with their ability or above expectation.
In addition, the quality of provision for children who required additional support with aspects of their learning was found to be good.
It was issues with leadership and management that caused it to fall into the inadequate bracket.
The co-educational school opened in 2011 following the amalgamation of the separate St John the Baptist Boys' and Girls' schools on Finaghy Road North.
Those schools served the parish of St Michael the Archangel since 1974.
Jeannette Chapman, the merged school's first principal, was placed on precautionary suspension last summer and is yet to return.
Inspectors reported that the quality of leadership and management was inadequate and said: "The staff from both schools have not developed sufficiently as a team since the amalgamation. A culture of uncertainty pervades the school which is impacting negatively on the ethos."
The report added: "Due to a complex and challenging situation, an acting principal and acting vice-principal have been in post since the end of May 2014.
"Over the last two years, the staff absence levels have been very high. In 2012/13, it was double the Northern Ireland average; in 2013/14 this had increased to almost four-times the Northern Ireland average.
"At the time of the inspection, there were four temporary teachers employed in the school."
The average number of days lost per teacher in all schools across the north in 2013/14 was 8.07.
The report also referenced serious issues relating to financial accountability. The senior leadership team was unable to produce a governors' annual report for 2012/13 and 2013/14 during the inspection.
Also, since the amalgamation, a large proportion of the building has not been used due to health and safety concerns.
"This adversely affects the morale of staff members and limits the potential of the building to meet the needs of the children and the wider school community. There is an urgent need to address the underlying issues and so maximise the potential of the whole building. There are significant health and safety issues."
INTO senior official Nuala O'Donnell said absence levels had improved significantly in the last year.
She added that the union disputed the report, which she said focussed a lot on historical problems rather than what had been observed at the time of the inspection.
"We have huge issues with the inspectorate. The current teaching, leadership and management of the school are satisfactory to good, and that is not reflected in the report," Ms O'Donnell said.
"There are no issues from parents. This is a school that is functioning well despite what happened in the past, but the staff is now being penalised for things that are beyond their control."
CCMS said it was working with the staff and governors to address the concerns raised.
The Department of Education said CCMS and INTO both raised issues about the publishing of the report and the inspectorate listened carefully to these concerns.
"However, the report was published to ensure the children, parents and guardians are aware of the findings and in order to assist the school, and those agencies which support it, to begin work on addressing the areas for improvement as soon as possible," a department spokeswoman said.
