Image copyright Getty Images Image caption Labour claims child poverty is set to rise by 400,000 between 2011 and 2015

The government has unveiled its new child poverty strategy - but plans to change the way it is measured have been put on hold.

Liberal Democrat Education Minister David Laws accused the Conservatives of "vetoing" improvements and said it was "very frustrating and disappointing".

Conservative Iain Duncan Smith also backed the move, but it is understood the Treasury blocked it.

The strategy restates the government's aim to end child poverty by 2020.

It lists a range of existing government policies which might help children living in poverty, including childcare support, free school meals, fruit and vegetable vouchers, discounts on energy bills and increases in the threshold for paying income tax.

The proposals have been put out for public consultation.

'Long diversion'

At the moment children are said to be in poverty if they live in a household with an income less than 60% of the national average.

This means that if there is a recession, for example, the average household income figure could fall, so fewer children are judged to be in poverty, even though their circumstances have not changed.

Changing the definition, critics would argue, could make it easier for the government to meet the target of eradicating child poverty by 2020. But the Treasury was worried about the opposite problem. Why the political split over child poverty?

The opposite happens when the economy grows - if average household incomes increase, more children might be deemed to be in poverty even though their parents' circumstances have not changed.

Work and Pensions Secretary Iain Duncan Smith wanted to introduce a more sophisticated measure - taking in to account whether children have access to a good education, a decent home, and a stable family - and had reached a deal with his Lib Dem colleagues, BBC political correspondent Iain Watson said.

"The Treasury are sticking to the line that they have not blocked a new measurement," Iain Watson said, "but they certainly have sent it on a long diversion".

Mr Laws told the BBC: "I can't get into the entrails of why the Conservatives have been unable to agree and come forward with a serious set of measures. They will have to explain that.

"What I'm not willing to do is to allow this key debate over measures which are so important in driving the right policies in future to simply be vetoed by one party."

'Common ground'

He said it was important to bring in new measures of child poverty "because ultimately they are the driver of policy in the future".

He added: "The Liberal Democrats have a very clear idea of what the new measures should be, and we're not going to allow the Conservative Party simply to end discussion of this."

He said the party would put new targets in their manifesto including narrowing the educational attainment gap between those from disadvantaged backgrounds and children from better-off families.

The Lib Dems have said there is a "lot of common ground" between them and Mr Duncan Smith on the policy.

In a joint article published in the Guardian, Chancellor George Osborne and the work and pensions secretary wrote: "To see why Labour's measure of poverty - defined as 60% of median income - is so discredited consider these perverse outcomes.

"Measured child poverty fell because the Great Recession reduced median incomes, but in the real world nobody's life was improved by that.

"Equally, raising the state pension results in higher measured child poverty. That doesn't make any sense."

'Squabbling'

But, they concluded, it was important "we take the time to get it right".

The Children's Society's Matthew Reed said: "The government's continued commitment to ending child poverty is welcome.

"But its strategy has no new ideas on how to make this a reality. It falls far short of what is needed to prevent a significant increase in the number of children living in poverty by 2020."

The Baptist Union of Great Britain, Methodist and United Reformed Churches released a statement arguing that the strategy contained no proposals "substantial enough to grasp the seriousness of the challenge ahead".

"Perversely the strategy trumpets measures that will actually increase child poverty," it continued.

'Beyond farce'

Labour's shadow work and pensions secretary Rachel Reeves said: "Child poverty is set to rise by 400,000 under David Cameron's government, while ministers squabble over the way poverty is defined.

"The row between George Osborne and Iain Duncan Smith does nothing to help working people who are £1,600 worse off a year because of the cost-of-living crisis.

"If David Cameron was serious about cutting child poverty he would scrap the bedroom tax, introduce a compulsory jobs guarantee, strengthen the minimum wage, incentivise the living wage and extend free childcare for working parents."

The former Labour MP who chairs the current government's Social Mobility and Child Poverty Commission, Alan Milburn, said: "A strategy which cannot be measured is meaningless.

"Despite taking more than a year to think about it, the government has drawn a blank, apparently unable to reach agreement on what a new set of measures should look like.

"The government has ended up in a no-man's land where it has effectively declared its lack of faith in the current measures but has failed to produce an alternative set. This is beyond Whitehall farce."