About 1.6m children in the UK are living in severe poverty, Save the Children says.
The charity, which found the highest levels of child poverty in Manchester and Tower Hamlets, in London, said the figure was a "national scandal".
And it said more children would be tipped into poverty by public sector job losses and changes to benefits.The government said it was "fully committed to the goal of eradicating child poverty by 2020".
Of the UK nations, Save the Children found Wales had the highest proportion of children living in severe poverty (14%), followed by England (13%) then Scotland and Northern Ireland (9% each).
It found 29 authorities across the UK had more than one in five children living in severe poverty.
