Plans to relax restrictions on the number of children a childminder can look after will not cut the cost of childcare, warn critics.
The plans, revealed today, have also been branded "a recipe for disaster" by a leading nursery organisation.
Liz Truss, the Children's Minister, announced this morning that childminders, currently restricted to looking after three children per staff member from the ages of one to five, will be able to look after four under new plans. She said this should drive down the cost of childcare.
The Department of Education said other changes intended to boost the professionalism of childminders and reduce costs to parents included making sure qualifications for staff are "rigorous and more demanding" and abolishing the rule where schools have to register with Ofsted before offering childcare.
But Amanda Coxen, director of Tinies Childcare, said: "Actually if you speak to the nurseries, it won't reduce costs at all as many are struggling to stay afloat.
"What the industry is worrying about is if the government does go ahead with this, how does it affect the quality? If you reduce the number of people caring for your children, how can that be good?"
Neil Leitch, chief executive of the Pre-school Learning Alliance, said: "We agree that childcare should be affordable but it needs to be adequately funded by the system not by dangerously tinkering with ratios."
Purnima Tanuku, chief executive of the National Day Nurseries Association, said: "Staff with higher qualifications will find it difficult to give larger groups of under threes the level of practical care they need."
She added that many parents did not want an increase in the number of children nursery staff are allowed to look after.
Truss defended the proposals saying that other countries such as Netherlands and France have similar ratios.
She said: "It is right that the government does everything it can to ensure the provision delivering early education is of the highest quality, staff are paid better, and childcare is affordable to parents."
Research by Tinies Childcare shows the cost of a full-time nursery place in London can be as much as £350 per week, and £260 a week in north-west England.