Failings in private nurseries that had been previously approved by Ofsted inspectors have been uncovered, in an investigation by BBC One.
Carer teases child with a biscuit at Little Treasures, Festival Way, Stoke
Verbal abuse of toddlers, breaches in basic hygiene and under-staffing were all secretly filmed by a BBC reporter posing as a volunteer.
Ofsted, the body responsible for guaranteeing nursery standards, has launched investigations into all the nurseries that were secretly filmed.
Meanwhile, a local council which partly funds one of the private nurseries featured in the programme has accused the BBC of scaremongering.
In Thursday's "Nurseries Undercover: The Real Story", the BBC secretly filmed staff shouting at children and, in one nursery, terms of abuse were used.
Reporter Lizz Brown also saw breaches in the minimum staff-to-child ratios outlined in Ofsted's guidelines and the flouting of basic hygiene rules such as hand washing after nappy changing.
Contrary to Ofsted regulations, Ms Brown was able to obtain voluntary work and was left on her own in sole charge of toddlers without proper checks on her background.
The only information one nursery had about her was her mobile phone number.
At Little Treasures, on Festival Way, in Stoke-on-Trent, the BBC found that some carers shouted and one staff member called children "minger" and "imbecile".
Nursery staff were caught on tape pulling children by the arm and, on one occasion, a member of staff joked about an incident when she frightened the youngsters.
Hygiene regulations such as wearing gloves and washing hands at the end of a nappy-changing run were not always observed - even when there was a stomach bug going around the nursery.
Childcare expert Marion Dowling, president of the British Association for Early Childhood Education and a former Ofsted inspector of nurseries, described the shouting as "verbal and emotional abuse".
It was inexcusable, she said.
"If the children are exposed to that behaviour day after day, I do feel they will become hardened to it and in the worst circumstances start to imitate that behaviour."
One mother, Paula Hudson, who withdrew her child from Little Treasures after seeing some footage said: "I can't believe I've seen something as bad as that where my son attends nursery.
"They just don't deserve to be in a job, especially looking after vulnerable kids that belong to somebody else."
Following the BBC investigation, four staff have been sacked from Little Treasures.
The nursery said in a statement that it had been "regrettably unaware of incidents of misconduct".
CCTV has since been installed in the nursery.
Staffordshire Police said it would be looking into issues raised by the investigation.
In another nursery, Petits Enfants on Church Road, Teddington, Middlesex, parents paid £145 a week for a full-time place for a child over two-years-old.
Carer asleep while in charge of sleeping children at Petits Enfants, Church Road, Teddington.
Yet the BBC was told by a worker that for months there had been no soap or cleaning materials in some of the toilets.
Children were expected to share the same potty without emptying in between.
One father at the nursery, Jon Mullen, told the BBC: "I think spot checks are the only way to make sure that people do what they should be doing day in and day out. I'd welcome that as a parent."
On two occasions the BBC found one nursery nurse at Petits Enfants asleep when he was meant to be in charge of a group of sleeping children.
The nursery said in a statement that "sadly it had not met the high standards" it set itself, and that this was unacceptable.
"We take the allegations very seriously and new procedures have been put in place," it said.
And at Bank House Nursery, in Radcliffe, Greater Manchester, the BBC found that minimum staff child ratios were not always observed.
The manager was aware that all staff who were left alone with children needed to be checked by the Criminal Records Bureau - yet the BBC's reporter was allowed to take children to the bathroom without any vetting.
Bank House said it did not believe the programme had a legitimate criticism of the care it offered.
A spokesman for Bury Council, which partly funds Bank House, defended carers' treatment of children and accused the BBC of scaremongering.
The local authority's time had been wasted on a "needless" investigation and the corporation had been "uncooperative" after the allegations were made, he added.
And investigations by the council, the police and Ofsted had found "nothing untoward".
Director of social services, health and housing Eeni Ioannides said: "We are left wondering whether the BBC, having spent time and money putting a reporter into the home, is simply now trying to justify the time and effort by running the story anyway."
Ofsted said it was concerned by the issues raised in the BBC report and was investigating all the nurseries that were secretly filmed.
Currently, Ofsted informs nurseries of the month of their inspection, which critics say allows some businesses to alter their staff rotas and practice in advance to ensure they get a good report.
Ofsted said it was considering introducing "next to no notice" inspections.
Real Story: BBC One, Thursday 12 August 2004, 2100 BST and live on the Real Story website.