As the school summer holidays get under way, food banks are urging people not to forget to donate supplies to their local centres.
The Trussell Trust, which runs over 420 food banks across the UK, says many children risk going hungry over the six-week break from school.
It says demand for emergency parcels for children rose significantly - by more than 4,000 - last July and August.
The government said it was helping families meet the cost of living.
Figures from the Trussell Trust show 67,506 three-day emergency food supplies were provided for children by its network in July and August 2016, compared with 63,094 in the May and June - an increase of 4,412 parcels.
The trust says nearly half (47%) of those 67,506 parcels went to primary-school-age children and over a quarter (27%) to children aged four and under.
It says, while it welcomes the government's decision to keep free school meals for infants in England, more must be done to help struggling families during the holidays.
'Close to crisis'
Samantha Stapley, operations manager for England at The Trussell trust, said: "Over a third of all the food distributed by food banks in our network consistently goes to children, but these new figures show five- to 11-year-olds are more likely than other children to receive a food bank's help.
"This highlights just how close to crisis many families are living - as a nation, we also must address the reasons why families with children are referred to food banks in the first place.
"We welcome the government's decision to maintain free school lunches for children during term time - the next step must be to help families during the holidays.
"Food banks are doing more than ever before, but voluntary organisations alone cannot stop primary school children facing hunger."
A spokeswoman for the Department for Work and Pensions said: "Employment remains the best route out of poverty.
"Record numbers of people are now in work, and we're helping millions of households meet the everyday cost of living and keep more of what they earn.
"We've doubled free childcare to help parents into work, and continue to spend over £90bn a year on support for those who need it, including those who are bringing up a family or on a low income.
"Budgeting advice and benefit advances are also available for anyone who needs more help."