A Sheffield nursery is under investigation by Ofsted following complaints from parents about the use of restraints on children.
The education watchdog says it is treating the probe into Lamb Setts Montessori Nursery in Mosborough 'as a priority', and police and social services have also been made aware of the concerns raised.
The Star has spoken to two parents who say they were shocked to learn youngsters were being restrained using a strap, and have since withdrawn their children from the nursery. Neither parent wished to be named, and both made it clear this method had not, to their knowledge, been used on their child.
The nursery declined to comment but The Star has seen a letter sent to parents by manager Christy Bakewell in which she attempts to address their concerns.
In it, she explains that the use of wrist straps is part of a strategy discussed with parents of special needs children, who may require close supervision to prevent them wandering into other units.
She says these strategies were not discussed with other parents or children 'in any depth', which she accepts was on reflection an 'oversight'.
She claims children may have been confused upon seeing other youngsters with these wrist straps or babies in chairs with safety straps, wrongly believing it was a punishment for being naughty.
A spokeswoman for Ofsted said: "We can confirm that we have received complaints from parents about the use of restraints and we are looking into this. We are treating it as a priority and liaising with relevant agencies."
One parent, who asked not to be named, said the issue came to light earlier this month after another family's child had refused to go to nursery, telling her parents 'I don't want to go in the strap chair'.
"When I asked my daughter, she said 'I'm a good girl so I don't go in the strap chair'," she said.
"But she said she'd seen another child who had been naughty get strapped in the chair and prevented from playing or having their snack.
"She said the strap was kept in a drawer and had been taken out and used as a threat to get children to behave."
She claimed the nursery had not treated parents' complaints with the seriousness they deserved, and believed staff identified by children as using 'inappropriate' restraint should have suspended as soon as the allegations were made.
She added that she was one of seven parents who had reported the nursery to Ofsted.
Another parent, who also asked to remain anonymous, said: "When I found out what had been happening I was so angry, and my daughter won't be going back there.
"The nursery's policy doesn't say anything about the use of restraints, even for children with special needs."
Ms Bakewell's letter states that in light of the concerns raised, all parents will now be informed of any special needs strategies falling outside its normal behaviour policy, dolls will be used to explain to other youngsters why some children need 'extra care', and the CCTV system is being updated.
South Yorkshire Police and Sheffield Council both said they were aware of parents' complaints and were supporting Ofsted with its investigation.