Nurseries and childminders will be allowed to look after more children as part of coalition efforts to cut childcare costs.

Staff are to be able to take charge of six two-year-olds rather than four while the ratio for under-ones will go up from three to four.

Education minister Liz Truss is to outline the changes, which have been criticised as lowering standards, as part of reforms that will see higher qualifications required of those caring for pre-schoolers.

However, ministers have still not finalised a much-heralded wider shake-up of childcare funding and tax breaks. Britain has some of the highest childcare costs in the world, meaning many mothers with two or more children find it does not make financial sense to work.

Ms Truss will tell an event at the Policy Exchange think-tank that the Government wants to introduce graduate-level Early Years teachers. An Early Years Educator qualification will also be created, requiring practical experience and at least a C grade in English and maths GCSE. But she is to insist that better wages are needed to improve the system in England, pointing out that nursery staff only earn £6.60 per hour on average.

Hailing the example of France, Ms Truss will say that easing rules on ratios can give nurseries the "headroom to pay higher salaries". She will add: "We have learned from other countries that deliver better-value and better-quality childcare."

Ofsted's director of early childhood, Sue Gregory, said: "Ofsted welcomes the Government's proposals to drive up further the quality of early education and childcare. We particularly welcome plans to introduce more rigorous training and qualifications for those working with young children."

The Pre-School Learning Alliance denounced the Government proposals as a "recipe for disaster", pointing to a recent survey of childcare practitioners which found that 94% were against changes to adult-to-child ratios. The Alliance's chief executive, Neil Leitch, said: "We are absolutely appalled by this fixation to alter ratios, despite the fact that those working in the sector are universally opposed to the proposal. This is a recipe for disaster and I hope those making this decision will be as enthusiastic in answering questions from concerned parents and the media when the consequences of their actions come to the fore."

The general secretary of the NASUWT teachers' union, Chris Keates, said: "The NASUWT has called consistently for more effective action to be taken to enhance the skills of the early years workforce and to improve the often highly unattractive pay and conditions of staff in the sector. However, planning to seek to secure higher qualification and pay levels within the workforce by sacrificing appropriate adult-to-children ratios is a flawed strategy."

Conservative MP Claire Perry, who advises the Prime Minister on childhood, said there were "furious negotiations" going on within the coalition Government about new financial help for parents with childcare, with an announcement expected in "weeks not months".