Some £88 million destined to help feed the poorest children is feared "lost", ministers have been warned.

Former welfare reform minister Frank Field raised concerns over what happens to cash from the free school meals (FSM) budget and called for the spending watchdog to investigate.

The Hungry For Change report said the issue of FSM money claimed but not taken in primary, secondary and special school is widespread across England, and estimated the amount could be around £88.3 million.

It added this is likely to be a "conservative estimate" as it only takes into account data on pupils who were absent from school on the census date, and does not include pupils who either skipped lunch or did not spend their full daily entitlement.

Independent MP Mr Field, who chairs the Work and Pensions Committee chairman, told the Commons: "If your parents pay for your dinners and the credits of those monies are put onto your card, if you're not at school for a particular reason to have your school dinner, the money is rolled over.

"But if you're a poor child that school dinner money of that day is cancelled.

"Now, our good academics have found for us there's something like £88 million a year is lost to those children and it goes somewhere - presumably to the companies that run the cards operating the actual dinner system.

"I'm so concerned about this, the sum itself is so horrendous without being increased in any way, I wrote to the new Comptroller and Auditor General to ask whether he would undertake an inquiry on behalf of those MPs who are interested in this issue to try and establish is £88 million a floor or is it an even larger sum.

"Because for poorer children who may not attend school on one day, it's probably because they're ill.

"So the following day they'd need extra food, we'd think as ordinary human beings, but the money they didn't spend yesterday - unlike their richer peers - has disappeared from their cards."

Mr Field described the issue as a "new nasty little vicious twist of stigmatising against poor children who draw upon our school dinners system".

Labour's Ruth Smeeth (Stoke-on-Trent North) also said she is concerned about what happens to children who qualify for FSM during the holidays and called on the Government to "make sure there is more food for our schools".

She raised the case of a school in her constituency which ran a holiday club to help feed hungry pupils where volunteers were expecting 40 families to turn up.

Ms Smeeth said: "On that day, having expected 40, 191 families came through the door.

"There is a need. There is a desire. We have a responsibility to help."

Ms Smeeth also highlighted what can happen when children do not get meals out of school hours.

She said: "I was told by someone who worked as a catering assistant at one school a story of a child who on Monday morning collapsed, fainted when he walked into school.

"It took a while to understand what had happened.

"It was 11 o'clock in the morning.

"He hadn't eaten since his free school meal on the Friday.

"He was given a sandwich and an apple given how close it was to lunch.

"He ate the sandwich and didn't eat the apple and put it in his rucksack.

"They said 'it's OK you're going to have lunch in a minute. It's absolutely fine, eat the food' and he went 'my sister is down the hall and she hasn't eaten either'.

"In the 21st century, in the 13th largest city in the country (Stoke) children are starving."

For the Government, Education Minister Nadhim Zahawi said: "All children should be able to access healthy and nutritious food at home and at school.

"This is an essential part of building a country that works for everyone and in which every child and young person can reach their potential."

Mr Zahawi said the Government is taking steps to help children access nutritious food, noting there is "much more we need to do and can do".