The government has been urged to draw up an emergency plan to help poverty-stricken children in Britain.
Figures revealing that 1.6 million youngsters live in severe poverty were condemned as a “national scandal” by Save the Children.
With unemployment rising and a shake-up of the welfare system, the charity fears the number of children living without the basics will rise unless action is taken.
Save the Children has analysed data for local authorities across the UK, which shows that in 29 areas more than one in five children lives in severe poverty.
The charity found Manchester and Tower Hamlets LBC have the highest proportion, with 27%.
Of the UK nations, Wales has the highest proportion of children living in severe poverty (14%), followed by England with 13%, then Scotland and Northern Ireland which have 9% each.
To measure severe poverty, Save the Children combines both income and material deprivation.
According to the charity, this means a single parent family with one child aged under 14 on an income of less than £7,000 or a couple with two children under 14 on less than £12,500 and going without things such as separate bedrooms for older boys and girls, proper birthday celebrations and having friends round for tea.
The charity wants the government to adopt this measurement because at present there is no official way to find out how many of Britain’s 13 million children are living in severe poverty.
It is also calling on the chancellor to announce an emergency plan in the next budget to channel new jobs into the poorest areas and increase financial support for low-income families.
Sally Copley, Save the Children’s head of UK policy, said: “If the government is to fulfil its commitments on child poverty, it must find a way of counting these children in greatest need.
“At the moment, these children are hidden from official view, and their plight unrecognised.
“If these children are to have a future, we must acknowledge their desperate need and urgently target government help towards them.”
A government spokesman said: “Our radical welfare reforms will benefit the poorest in society, helping 350,000 children out of poverty, and targeting support at those who need it most to make work pay and break the benefits trap. We know that work is the best route out of poverty.”