The Joseph Rowntree Foundation (JRF) said almost 400,000 more children and 300,000 more pensioners are living in poverty than four years ago, with little progress in reducing poverty among working age adults.
Its state of the nation report said poverty rates increased last year, leaving 14 million people living in poverty, including four million children and 1.9 million pensioners.
New threats are emerging to the poorest households, including rising housing costs, higher food and energy bills, debts and not being able to contribute to a pension, said the social research group.
The Government was urged to end the four-year freeze on working age benefits and tax credits and to invest in a more ambitious house-building programme to provide genuinely affordable homes to rent and buy.
Campbell Robb, chief executive of the JRF, said: “These worrying figures suggest that we are at a turning point in our fight against poverty.
“Political choices, wage stagnation and economic uncertainty mean that hundreds of thousands more people are now struggling to make ends meet. This is a very real warning sign that our hard-fought progress is in peril.
“Record employment is not leading to lower poverty, changes to benefits and tax credits are reducing incomes and crippling costs are squeezing budgets to breaking point.
“The Budget offered little to ease the strain and put low income households’ finances on a firmer footing.
“As we prepare to leave the EU, we have to make sure that our country and our economy works for everyone and doesn’t leave even more people behind.”
The poverty indicator used in the report is when a family has an income of less than 60% of median income after housing costs.
Alison Garnham, chief executive of Child Poverty Action, said: “As today’s report shows, we know how to reduce child poverty in the UK - we’ve done it before.
“Yet at the start of a sustained rise in the rate of child poverty - bewilderingly - there is inaction. The question the report begs is why are we not investing in our children?
“Families with children have had a decade of cuts to their incomes and the damage is showing. Unless there is action now to protect the living standards of low-income families, we will pile up problems for future generations and for the UK economy.”