The Children's Society has warned that changes to the welfare system could leave England's poorest youngsters without free school dinners.
Free school meals are linked to the benefits which are being merged into a single Universal Credit in 2013, and the charity fears it will leave some 120,000 families - with around 350,00 school children - worse off.
It estimates that it would cost £500m to give free school meals to all families on the Universal Credit scheme, and claimed that ministers were considering limiting it to households with an income of around £145 a week.
Elaine Hindal from the charity said that government should extend the availability of free meals so no child goes without.
She said: "The Government has an unique opportunity to extend free school meals to all low-income working families, so that no child living in poverty misses out.
"This would be in line with the Government's aim to make work pay by paving the way for many families to return to employment and help lift them out of poverty."
According to the charity's Fair and Square report, 2.2 million English schoolchildren are living below the poverty line. More than half of these youngsters are not receiving free school meals while 700,000 are not entitled to the dinners, it revealed.
The Children's Society has launched a petition to call for all children in poverty and low income families to be entitled to free dinners.
If you believe children need at least one square meal to grow and thrive, you can sign the petition here.
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