Children were sent home from a nursery in Southgate this week after an investigation was launched by the schools' inspector Ofsted.
Parents of the 70 children who attend the privately-run Wonderland Nursery in Burleigh Parade, were informed of the decision by phone late on Monday.
The nursery will be closed until January 5 subject to a specialist inquiry, which is only launched when children are feared to be at risk.
An Ofsted (Office for Standards in Education) spokeswoman confirmed: "Ofsted served a suspension notice on Wonderland Nursery on Monday.
"This notice requires the nursery to close immediately to allow investigations to take place.
"Suspension notices are issued only when children are believed to be at risk. They last for six weeks, but Ofsted is able to apply to the Care Standards Tribunal to extend this if it requires more time to complete investigations.
"Equally, the proprietor may appeal to the same tribunal to have the suspension notice lifted if they believe it is unjustly served, or that circumstances have changed.
"We have no further comment to make at this present time."
Wonderland Nursery looks after 70 children aged three months to five years. It practices Montessori, a holistic method of teaching popular with celebrities, which encourages children to be independent.
Parents are now urgently searching for alternative child care places.
Parent Daniel Molloy, whose two-and-a-half year-old son attends Wonderland Nursery, said: "My wife took the call at 10pm last night saying Ofsted had closed the nursery down until January 5, but they didn't give a reason.
"I was a bit shocked to get the call so late in the evening. My child has been there for six months. I have spent today trying to find a new nursery."
Another concerned parent added: "All the parents seem to be left in the dark and have been calling each other to find out what's going on. It's all very odd."
A nursery spokesman said: "We have appealled against this suspension."
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