Parents are going without meals or surviving on cereal to help feed their children over the school holidays, an MP has said.
In a letter to ministers, Frank Field said evidence given to his Work and Pensions Select Committee by mothers was "profoundly distressing".
He urged the government to take immediate action to help those struggling without free school meals.
The government said it recognised that some families needed more support.
In his letter to new Education Secretary Gavin Williamson and Work and Pensions Secretary Amber Rudd, independent MP Mr Field said: "We heard about parents going without meals and surviving on cereal just to make sure their children were fed.
"We heard about families being plunged into debt, just to get by."
He urged them to extend a pilot scheme which supports children eligible for free school meals during the summer break.
Mr Field also raised concerns about the cost of school uniforms and with new benefit system Universal Credit, while urging the government to make progress on extending support for holiday schemes.
The committee plans to hear further evidence on this issue in the autumn alongside the Education Committee.
The government says it is investing £9m in free summer holiday clubs and continuing to spend £95bn a year on working-age welfare to support families.
But charities are also calling for more action. Gingerbread, which campaigns on behalf of single parents, says nearly half of them live in relative poverty, and in particular, need more affordable childcare.
The Child Poverty Action Group said: "Child poverty isn't just a problem in the school holidays, and it goes far beyond those eligible for free school meals."
Meanwhile, the Work and Pensions Committee have published a separate report on poverty and destitution.
It suggest that while poverty rates are much higher in households where no-one works, almost one in 10 households with children where all adults work full-time are in poverty.
According to the Social Metrics Commission, whose measurements the report recommends the government adopt, there are 8.3m working-age adults and 4.6m children are in poverty in the UK.
Mr Field said the government had no effective strategy to increase the life chances of poorer children and had failed to recognise the "unacceptably bleak picture emerging as it shreds our social safety net".
However, the government said it was helping people to improve their lives through work and ensuring those on a low income keep more of what they earn.
There are more people in work than ever before and wages continue to outstrip inflation, it added.
The report comes after a UN special rapporteur found Poverty in the UK to be "systematic" and "tragic". The UN report said "ideological" cuts to public services since 2010 have led to "tragic consequences".