An explosion in poverty-related hunger in Britain is putting the government in danger of failing to meet its international human rights obligations to its most vulnerable citizens, charities have warned.

The UK is a signatory to a UN economic and social rights convention that sets out minimum standards of access to food, clothing and housing.

Campaigners say austerity measures could put the UK in breach of the convention as welfare cuts threaten to leave hundreds of thousands of low-income households unable to afford to eat regularly and healthily.

A 70-strong consortium of charities, including Crisis, the Citizens Advice Bureau, Age UK, the Disability Rights Alliance and the Child Poverty Action Group, has been formed to monitor the growth in UK food poverty, with a view to the possibility of triggering a formal UN investigation.

The consortium says the huge rise in emergency foodbanks over the past two years, and widespread evidence that children are arriving at school hungry and that poorer families are facing a stark financial choice between "heating or eating", will be exacerbated by welfare reforms that come into force in April.

The combined impact of policies such as the overall benefit cap, local housing allowance limits, bedroom tax, cuts to tax credits and council tax benefit and the freeze in the value of welfare payments will have devastating consequences for Britain's poorest, it says.

"For the first time in the UK you have got a developed country, the seventh richest in the world, unable to ensure working people can feed, clothe and shelter themselves," said Jamie Burton, chairman of Just Fair, the charity leading the consortium.

"The rapid spread of UK food poverty shows that we are living in desperate times. Children are going to bed hungry and families are facing the distress and humiliation of needing emergency food parcels, some having had to walk for miles [to get them]. We believe this is wrong."

The warning comes as the UN special rapporteur on the right to food, Olivier de Schutter, visits London to deliver a lecture on Monday on the growth of food insecurity in developed countries.

De Schutter caused controversy in Canada last year after he published an official UN report critical of what he said was the failure of the welfare system to meet the basic food needs of a growing number of its poorest citizens.

The report noted the "staggering" fact that one in 10 families in Canada lived in food insecure households. It found that charity-based food aid had proliferated and nearly 900,000 Canadians were accessing foodbanks each month.

Traditionally, the UN rapporteur has focused investigations on developing nations, but the Canada report sent a clear signal that the right to food security in western countries should be taken seriously as austerity policies take hold.

His UK visit is not a formal one, and protocol suggests he will not comment specifically on UK food poverty issues. Campaigners, however, say they are actively considering ways of triggering a formal UN investigation.

The End Child Poverty coalition will this week publish poverty maps showing that hundreds of thousands of children will fall into poverty in the next few years as a result of spending cuts and welfare reform.

One of the most robust sources of food poverty data is compiled by the Trussell Trust, which currently oversees 309 foodbanks and is opening new ones at the rate of three a week. In 2010 it fed 60,000 people. In the last 10 months it has issued food parcels to 245,000.

Trussell Trust figures are thought to be indicative of a much wider problem, as they do not capture the growth of informal emergency food interventions by hundreds of churches, housing associations, and poverty charities.

Chris Mould, the director of the Trussell Trust, said: "Our message is clear. We want greater recognition of the depth of the food poverty problem. We want to see politicians engage seriously with the question of how best we tackle this issue."

Labour MP Kate Green, a patron of Just Fair, said: "The rise in the use of foodbanks clearly reflects increasing hardship and the difficulty families face in making ends meet, as prices rise and incomes fail to keep pace.

"This is being caused by government austerity measures which mean benefits and tax credits fail to keep pace with inflation, wage squeezes and freezes, and particularly high rises in price of food and energy – non-discretionary purchases which use up a disproportionate amount of a low-income household's budget."

A DWP spokesperson said: "Our welfare reforms will improve the lives of some of the poorest families in our communities, with the universal credit simplifying the complex myriad of benefits and making 3 million people better off.

"We welcome the contribution of voluntary organisations for the work they do with local communities. That is why Jobcentre Plus for the first time is now referring people to their services."