EARLY-years inspectors are turning into detectives and urging parents to inform police about illegal childminders.
Teams from the Office for Standards in Education have also been using surveillance to assist investigations into childminders who are not registered or are in breach of regulations.
Each of the eight regional early-years offices has its own team of investigators who have been monitoring complaints.
The first teams were set up a year ago this month, when OFSTED took over responsibility for the registration and inspection of childminders and day-care.
But managers say the investigators are only now starting to use their full legal powers, which include entering childminders' premises, seizing documents, and shutting down businesses.
And an investigation by the London team last week led to the conviction of a Hammersmith and Fulham woman, who was fined pound;1,500 for unregistered childminding and ordered to pay OFSTED's legal costs.
The team manager - who wishes not to be named for security reasons - said the group had investigated more than 100 cases in London where there had been concerns about safety.
"There's puzzlement from some of the child protection people we meet," he said. "They say 'What are OFSTED doing here? Shouldn't they be inspecting primary schools?'.
"In the Hammersmith case, the woman was looking after 14 children, and she didn't know all their names or how to contact their parents if they suffered an accident."
A standard complaints investigation team consists of six officers, who are often former police or benefits fraud investigators. They are led by two senior childcare inspectors, and backed by several administrative staff.
The teams work in close partnership with police and social services, and claim to use surveillance including photographing people entering or leaving the minder's property, or their powers to enter that property, as last resorts.
Most of the cases they investigate come from complaints to the OFSTED early-years helpline. On a typical day last week the London team received 144 calls, 20 of which were complaints about individual childminders.
Dee Gasson, a senior policy adviser to OFSTED, said that the tip-offs ranged from moans from neighbours about the way parents parked their cars to serious abuse allegations which were then passed on to the police.
She said that the investigators had an increasing number of measures they could take and would always try to help childminders meet the regulations before taking action, except in cases where there was an immediate risk.
Except for nannies and babysitters, anyone who accepts payment for looking after children under the age of eight, and is not their relative, must be registered with OFSTED.
Before registration, all childminding applicants have a home visit by an inspector, who checks the suitability of the location and decides how many children can be cared for there safely.
The childminder, and all adults who live on the premises, also undergo full criminal checks.
Anyone wanting information on being a childminder, or to report illegal practice, can call the OFSTED early-years hotline on 0845 601 4771.