The United Nations’ poverty envoy has warned Rishi Sunak that unleashing a new wave of austerity in this month’s budget could violate the UK’s international human rights obligations and increase hunger and malnutrition. Olivier de Schutter, the UN rapporteur on extreme poverty, said he was “extremely troubled” by likely multibillion-pound spending cuts – including possible real-terms reductions in welfare payments to millions of the nation’s poorest families. The government is due to unveil a crunch budget on 17 November to fill an estimated £40bn black hole in the public finances using tax rises as well as spending cuts. Speaking to the Guardian, the UN-appointed official, who has recently been investigating extreme poverty in Kyrgyzstan, Lebanon and Nepal, said: “This is the worst time to impose such cuts. You do not impose austerity measures when the whole population is facing a cost of living crisis. What you do is you raise taxes on the rich, you raise taxes on corporations.” De Schutter, a Belgian, added: “The immediate reaction of many households will be to reduce the quality of diets and ultimately the consumption of food. “For children, learning is more difficult when you have an empty stomach and that is becoming a reality in the UK. That should not be allowed to happen.” His intervention came amid warnings by the Resolution Foundation thinktank that cuts should not exceed £20bn – a real-terms freeze in spending – which would bring in a new era of austerity. It wants taxes to take more of the load. Sunak and his chancellor, Jeremy Hunt, are considering whether to increase benefits by less than inflation, a real-terms cut, as well as raising some taxes – possibly by freezing income tax thresholds. It has been reported that they last week agreed major cuts must be made to Whitehall departments and that real-term pay cuts are being considered for public sector workers including nurses, police officers and teachers. On Thursday the Bank of England will announce if it will increase interest rates again, putting further pressure on household finances, as it struggles to bring down inflation from about 10%, with the economy heading towards a recession. The Confederation of British Industry has warned against a “doom loop” of cuts to public spending and tax rises. De Schutter’s decision to speak out reignites tension between the UN and the UK government over poverty after his predecessor, Australian Philip Alston, made a 10-day visit to the UK in 2018 and concluded Conservative governments had inflicted “great misery” with “punitive, mean-spirited and often callous” austerity policies driven by a political desire to undertake social re-engineering rather than economic necessity. The government, led at the time by Theresa May, hit back, saying it “completely disagreed”. De Schutter has now said he would be keen to make a follow-up visit, which would have to be agreed by the UK government, “given the context that we are facing now, the very high rate of poverty and the austerity that is kicking back”. “There is a clear requirement in human rights law that you do not adopt retrogressive measures,” he said. “Not aligning social benefits or minimum wages with increased costs of living is a retrogressive measure so the government would be violating its international human rights obligations if it were to cut down on social benefits [in real terms], and that is what we may see happening.” In response, a Treasury spokesperson said: “Our number one priority is economic stability and maintaining confidence that the UK is a country that pays its way. “The prime minister and chancellor have been clear that this will require some difficult decisions, but protecting public services and the most vulnerable will be prioritised.” They also cited the existing energy price cap and £1,200 cost-of-living payments to the most vulnerable households. Like Alston, De Schutter is a leading international human rights lawyer. He previously served as the UN rapporteur on the right to food, was a member of the UN committee on economic, social and cultural rights and is a professor at UC Louvain in Belgium and Sciences Po in Paris. The UK is a party to the International Covenant on Economic, Social and Cultural Rights which states that any retrogression in rights in one area must be compensated by progress in other areas. For example, if housing becomes more expensive, healthcare becomes cheaper. Already, 22% of the UK population – 14.5 million people – live in relative poverty, according to the Joseph Rowntree Foundation. Uprating benefits in line with earnings, instead of inflation, would result in 450,000 more living in poverty in 2023-24 and 250,000 more living in “deep poverty” - 50% below the poverty line – according to the Legatum Institute, a London-based conservative-leaning thinktank. “There is another path possible than austerity increasing poverty in the UK and this other path is much more progressive, increasing taxes on the wealthiest households and on corporations, financing the continuation of the energy price guarantee and the indexation of social benefits in line with inflation,” said De Schutter. “That pathway is what international human rights require from the UK.” De Schutter has previously warned that the reversal of the £20 a week uplift to universal credit during the pandemic would increase poverty levels in the UK. “These warnings were not heeded and now Britain is facing a situation in which already very high levels of poverty will raise further as a result of the cuts that are anticipated to be announced on 17 November,” he said. “So I am extremely troubled by what is happening.”