A Montessori nursery has been forced to close while officials investigate claims that a member of staff used a wrist strap to restrain children who misbehaved in a chair.
Lamb Setts Montessori Nursery is under scrutiny by Ofsted following concerns raised by several parents earlier this month.
One parent said complaints made about the use of the "strap chair" to "get children to behave" were not taken seriously.
The mum, who wished to remain anonymous, said: "When I asked my daughter, she said 'I'm a good girl so I don't go in the strap chair'."
Ofsted says the pre-school in the Mosborough area of Sheffield, had failed to notify the watchdog of an allegation made against a member of staff and the use of restraints.
A statement by the watchdog read:
A letter to parents from manager Christy Bakewell read: