The government's commitment to keep child poverty steady over 2012 to 2013 has been debunked by the Institute for Fiscal Studies (IFS).
A report just released shows that relative poverty amongst children will shoot up by approximately 300,000 between 2010 and 2014 - the period of the government's spending review.
Robert Joyce, who wrote the report, said: "Among all children and working-age individuals, we forecast a rise in relative poverty of about 800,000 and a rise in absolute poverty of about 900,000 between 2010-11 and 2013-14.
"We find that the coalition government's measures act to increase poverty among these groups slightly in 2012-13, and more clearly in 2013-14."
The Child Poverty Act passed this year commits the government to scaling back relative child poverty by ten per cent and absolute child poverty by five per cent by 2020-21.
Ominously for the government, Mr Joyce added: "Meeting the legally-binding child poverty targets in 2020 would require the biggest fall in relative child poverty after 2013-14 since at least 1961."
The largest reduction in child poverty under the previous government was 4.8% over the six years to 2004-5, while the reductions needed between 2014 for the deadline in 2020 would have to be 10.5%.
Shadow work and pensions secretary Douglas Alexander said: "This revealing report from the respected IFS flatly contradicts David Cameron's promise that there would be no increase in child poverty.
"George Osborne has imposed billions of pounds worth of cuts to housing benefit and tax credits in this parliament and all Iain Duncan Smith has got out of it is a promise of reform in the next parliament."
Tim Nichols, speaking for the End Child Poverty campaign called for the government to immediately institute a child poverty committee to bring expertise to bear on addressing the problem.
He added: "Claims that the cuts meet the fairness test will now sound desperate and groundless.
"Even as incomes fall for typical households, the incomes for the poorest families will fall faster still and absolute child poverty will increase for the first time in fifteen years.
"Urgent action is needed to prevent a collapse into poverty for hundreds of thousands of children."
Meanwhile, Treasury claims that child poverty would not be negatively affected by the spending review in 2012-13 were accounted for by the fact the government figures didn't take into account changes in housing benefit, the IFS claimed.
The projections are based on tax and benefit changes launched by the new government along with predicted demographic changes.
Today's report adds to the chorus of criticism levelled by the IFS at government plans, following an equally scathing report on the coalition's decision to scrap educational maintenance allowance (EMA).
Senior coalition figures including Nick Clegg have attacked the thinktank's methodologies, but have liberally quoted from a recent IFS report branding tuition fees proposals more progressive than those of the previous government or Lord Browne.
The government has also commissioned a report by Labour MP Frank Field to devise better ways of measuring poverty based on 'life chance indicators', rather than the current system of defining relative poverty as a situation where an individual lives in a household the income of which is less than the median for that year.