Almost a quarter of a million school pupils who are eligible for free school meals could be missing out, according to fresh analysis.
The Liberal Democrats have warned that 234,500 children are not receiving them because their parents or carers have not applied.
The party has called on the Government to set up an automatic enrolment process, which could be done using social security records, to stop vulnerable children from missing out.
The Department for Education, who released the figures in response to a written question to ministers from the Lib Dems, estimated that more than one in ten (11%) school pupils entitled to free school meals are not registered for them.
In January, around 1.9million pupils in England were registered for free school meals, including 1,075,994 pupils at state-funded primary schools and 747,143 pupils at state-funded secondary schools.

As well as not getting a healthy school lunch, unregistered children lose out on Pupil Premium funding of up to £1,385 per year to support their learning.
If none of these unregistered pupils had previously claimed free school meals in the last six years, schools could be missing out on over £275million in funding, the Lib Dems calculated.
The Mirror’s Free School Meals for All campaign calls on the Government to provide free school meals for every primary pupil in England.
Around 800,000 children living in poverty miss out on free school meals due to strict eligibility rules - and the true number is expected to be higher as the cost of living crisis bites.
Liberal Democrats education spokeswoman Munira Wilson said: “This cost-of-living crisis is having a devastating impact on child poverty and hunger. Yet thousands of children are suffering needlessly because their families don’t know that they are entitled to free school meals or that they need to apply for them.
“Government ministers are standing idly by while children go hungry, expecting them to learn on empty stomachs. They have chosen not to step in and help.
“Parents should not have to jump through additional hoops to ensure their children are well fed when the Government already knows which families are entitled to free school meals.
“Better still, the Government should invest in our children by backing the Liberal Democrats’ plans for school lunches. Every child on Universal Credit should receive a free school meal so that no child is sitting starving in a classroom.”
Henry Dimbleby, who authored the National Food Strategy for Boris Johnson, said the situation was “worse than it’s ever been”, with teachers bringing in food for hungry pupils and parents having to go without in order to feed their kids.
In a boost to the Mirror’s campaign, the Government food tsar last week called on Rishi Sunak to extend free school meals to more needy kids for Christmas.
A DfE spokesman said: “We understand the pressures many households are under, that is why we are supporting more children and young people than ever before.
“Over a third of pupils in England currently receive free school meals in education settings and we have just announced a further investment in the National School Breakfast Programme, extending the programme for another year until July 2024 backed by up to £30million.
In addition, eight million of the most vulnerable households will get at least £1,200 of cost-of-living support this year on top of benefit from the Energy Price Guarantee - meaning they will be eligible for support which exceeds the average rise in energy bills by hundreds of pounds.”
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