A headteacher and five members of teaching staff at a Lancashire primary school have been suspended amid concerns over the wellbeing of pupils.
Parents of children at Revoe Primary School in Blackpool were told the "professional judgment" of the six employees had been questioned when isolating children "during challenging behaviour".
The Blackpool Gazette newspaper reported the alarm was raised over claims a child was placed in a room said by one parent to be the size of a cupboard.
Headteacher Cath Woodall was among those suspended as Blackpool Council and Lancashire Police launched an inquiry, although the council said it did not believe any child had come to harm.
In a letter to parents, Charlotte Clarke, the council's head of universal services and school effectiveness, wrote: "Before half-term Blackpool Council became concerned about the professional judgment made by these staff in relation to the wellbeing of pupils when isolating them during challenging behaviour.
"This has led to six members of staff being suspended. The suspensions are a neutral act to allow a full investigation to take place as quickly as possible.
"I realise this will be concerning news and I am writing to reassure you that swift action has been taken and the priority of the council is always the wellbeing of pupils."
An experienced headteacher had been drafted in while the investigation continues and temporary teaching staff were also in place, the letter added.
In a statement, Councillor Sarah Riding, the council's cabinet member for education and schools, said: "Before half-term we were made aware of an issue at Revoe Primary School that raised concerns to us about the professional judgment made by a number of staff in relation to pupil wellbeing. These concerns have led to the suspension of six members of staff while a full investigation is carried out. It would not be appropriate to comment further on the nature of the investigation until it has been concluded.
"Although we have no reason to suspect any child has come to harm this is a serious situation that needed immediate action to be taken. In the meantime temporary staff have been recruited and there will be no disruption to children's learning. All parents will receive a letter explaining the current arrangements in place."