Children going hungry in the school holiday is a "significant human rights issue for Scotland", the Scottish commissioner for children and young people has said.
Bruce Adamson called on the Scottish and UK Governments to gather accurate data on the extent of the problem.
Ahead of a visit to a Dundee food bank on Tuesday, the commissioner praised schemes aimed helping children stay well fed in summer such as primary schools clubs across Glasgow and West Dunbartonshire and a summer holiday meals scheme in Dundee.
But he said holiday hunger should be eradicated.
Mr Adamson said: "While these schemes provide a vital safety net, we need to see holiday hunger within the broader context of poverty and food insecurity.
"The issue is not just about food. Holiday hunger and child poverty is a significant children's rights issue in Scotland.
"A sustained, systematic and human rights-based approach at national and local level is needed to address and eradicate it. "
He added: "No child should be going hungry in the holidays. Children have a right to be free from hunger, food insecurity and malnutrition.
"Experiencing food insecurity as a child impacts negatively on physical health, mental health, and developmental outcomes and is a violation of their rights.
"It will shortly be the end of the school holidays and many children will have had a great summer break. Others will be less fortunate. For some children, school holidays can be a difficult time.
"Not only do they miss out on much of the play, culture, and informal education that the summer provides, many return to school in a worse state of health than at the start of the holidays which impacts on their ability to learn.
"It is not only having to pay for meals children usually get free at school, but there are additional costs for working parents.
"Then there are those hidden 'holiday costs' that many take for granted; days out and little treats.
"For many these are unaffordable luxuries as life simply becomes about surviving the holiday period, rather than enjoying it.
"Last year, the UN Committee on the Rights of the Child raised concerns that Scotland didn't have accurate data on the scale of food insecurity.
"We are seeing the effects of this right now across Scotland - we know children are going hungry, yet we do not know the full extent of the problem."
A Scottish Government spokeswoman: "No child should be going hungry and tackling poverty and inequality is a key priority for this government.
"Local authorities have the flexibility to provide meals to children outwith term time and some chose to use this flexibility during school holidays by providing holiday lunch clubs.
"In addition, we have already invested over £350 million in welfare mitigation measures, in addition to our £1 million Fair Food Fund which supports projects which promote dignity and harness the social potential of food to connect people and develop sustainable solutions to food poverty.
"The independent short life working group on food poverty recommended in its report published June 2016, that greater measurement of food insecurity was required.
"The Scottish Government has therefore taken steps to better measure the full range of food insecurity in Scotland.
"Three questions on food insecurity in Scotland will be included in the Scottish Health Survey 2017.
"Thereafter, the full United Nations food insecurity question set will be included in the SHS from 2018 onwards.
"This will allow internationally comparable baseline data on food insecurity in Scotland to be available in 2019 with further data sets available annually thereafter."
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