Deputy Prime Minister Nick Clegg has insisted that childcare policies must be led by evidence after signalling he did not support Norfolk MP Elizabeth Truss' plans to loosen ratios in nurseries.

Mr Clegg said discussions were continuing in Government but responses to a consultation on plans to relax the restrictions put forward by the childcare minister had highlighted problems with the proposals.

He said he was 'absolutely passionate' about improving the quality and availability of childcare but 'we have got to get this right'.

Mr Clegg also questioned whether any change in policy would result in cheaper childcare costs for parents.

Asked during his phone-in show on LBC 97.3 if the Prime Minister was aware of his concerns, Mr Clegg said: 'We have been talking about this for weeks and weeks.'

The policy emerged after months of wrangling between the coalition parties.

From September, the ratio for children aged under one had been due to rise from three per adult to four.

Each adult would be able to look after six two-year-olds instead of four, but the ratio for three-year-olds would stay at eight or 13 children per adult, depending on whether a qualified graduate was present.

Ms Truss has argued that the changes would lower childcare costs and allow professionals in the sector to be paid higher salaries.

But Mr Clegg said looking after four two-year-olds was 'already quite a handful'.

He said: 'I have got young children ... they have been through nursery so I know how much parents will really care that we get this right in terms of improving both the affordability of childcare, which we must do, but also the quality.

'What the Department for Education did is they consulted and they said is it possible to have an adult look after more children, so instead of four two-year-olds ... go up to six two-year-olds. I think four is already quite a handful, just imagine if they go up to six.

'Can you do that at the same time as raising quality? A lot of people basically got back in the consultation and said this isn't going to work, particularly for very small children, it isn't necessarily going to be passed on in terms of cost savings to parents.'

He added: 'We have got to get this right, we are still discussing this within Government.'

Mr Clegg insisted that his stance on the ratio would not affect wider reforms to childcare, including tax breaks worth £1,200 for families where both parents work.

He said: 'I am absolutely passionate that we should do more as a country to make sure that childcare is of better quality but also more affordable.

'This is not a great ideological thing, this is just about getting it right for parents up and down the country.

'When the last government changed the so-called ratios and allowed an adult to look after more young children, they did it for three and four-year-olds, it had almost no effect in reducing the cost for parents whatsoever.

'So you do need to be led by the evidence and that is what I will continue to do in the debate.'