A new study has revealed that nearly two-thirds of children in poverty are living with parents who work.
While levels of absolute child poverty were the same between 2009/10 and 2013/14, those living in a working family grew from 54% to 63% as wages lagged behind inflation, The Institute for Fiscal Studies (IFS) found.
It warned that benefit cuts announced in Chancellor George Osborne's Budget could push up absolute poverty for working-age households over the next five years
It expects planned rises in the minimum wage will fail to match welfare reductions.
The IFS said the decline in real-terms earnings since 2009, after inflation is taken into account, has forced the proportion of children who are in absolute poverty despite their parents working up from 19% to 21%
Child Poverty Action Group boss Alison Garnham said the report showed the "absurdity of the Government's attempt to amend the Child Poverty Act to say there's no such thing as working poverty".
A Government spokesman said that the number of people in in-work poverty is 200,000 lower than at its peak in 2008/09.The spokesman said: "This report recognises that rising employment has led to increases in the proportion of children living with working parents. And we know that the proportion of people living on low incomes is at the lowest level since the mid-1980s."