The headteacher and two teachers from a Norwich academy have reportedly left the school.
It is understood that on the last day of term, on Tuesday, staff from the Heart Education Trust told Heartsease Primary Academy headteacher James Julian and two other teachers that their contracts were terminated.
The decision reportedly came within their six-month probation period.
Scott Lyons, National Education Union (NEU) Norfolk spokesperson, said: 'Members have been in touch because they are very angry and upset that three colleagues have been sacked the week before Christmas.
'They were particularly upset by the use of the probation period policy.'
It is not clear what is behind the decision, but it is believed that parents are yet to be told.
Christina Kenna, chief executive of the Heart Education Trust, was contacted for comment and she said the trust's policy was that 'all personnel matters are treated in the strictest of confidence'.
We asked for further clarification, and she did not respond.
The school, which had 525 pupils as of May, was rated outstanding by Ofsted in May last year.
Its key stage two SATs results for 2017, which were released last week, showed that 42pc of its 48 pupils met the government's expected standard in reading, writing and maths.
Mr Lyons said the union was against the use of probation periods in schools and said teachers were already subject to 'continuous and rigorous scrutiny' over their performance.
'There are processes in place to challenge and support teachers if leaders feel it is needed,' he added.
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