The United Nations’ expert on extreme poverty and human rights has said he is considering whether to brand the UK’s benefits sanctions regime “cruel and inhuman”, following a two-week audit into the impact of austerity in Britain over the last decade.

The UN rapporteur, Philip Alston, is preparing what is expected to be a hard-hitting report following a months-long investigation of poverty in Britain which ended with a 10-day tour of some of the poorest areas of the UK.

It follows previous audits by Alston in Ghana, Mauritania, China and the United States. He visited some of the poorest neighbourhoods in Newcastle, Glasgow, Belfast, Essex and London and met people who had seen their benefits sanctioned under welfare reforms, some of whom had been left without enough money for food and heating.

“Whether I characterise it as cruel and inhuman, I will see how I feel on Thursday night when I am finishing writing my statement,” he told an audience of fellow human rights lawyers and activists at his final public event this week. “I am aware that many of the people who have experienced those sanctions have characterised them in that way.”

Alston said he heard “some pretty horrendous stories” about how disabled people are faring under the new universal credit system, and described the poor as “easy victims”.

“Attacking the poor is easy and they as a result suffer highly disproportionately in terms of their civil and political rights,” he said.

Alston is considered one of the world’s leading legal experts in the field of economic and social rights and is expected to spell out his view on the impact of austerity, local government cuts, universal credit and the possible impact of Brexit on poverty in Britain. He will also report on automation within the benefits system, aided by new technologies such as artificial intelligence.

He has a reputation as a strident critic, becoming embroiled last year in a public row with the Trump White House which he accused of pursuing policies that deliberately forced millions of Americans into financial ruin while lavishing vast riches on the super-wealthy.

The UN rapporteur has no direct power, but is considered an influential voice by many supporters of human rights.

“If the report is weak it will disappear and sink like a stone,” he said. “Let’s see what happens in this case.”

Koldo Casla – policy director of Just Fair, which campaigns for economic and social rights in the UK – said the visit was already a success because it has “created unprecedented interest in media and civil society and, more importantly, among people with direct experience of living in poverty”.

“We are eager to read and use his final report in a few months, but the most significant contribution is that Alston has listened carefully and has been a loudspeaker for hundreds of people that are too often paid very little attention to,” he said.

Alston held meetings with government ministers in London who told him “there wasn’t austerity”, he said. He met Esther McVey, who resigned as work and pensions secretary on Thursday.

He asked what Theresa May was talking about when she said she wanted to end austerity if it didn’t exist. “I didn’t get a particularly good answer to that,” he said.

He also said he had received “very surprising responses on the part of government to food banks”.

Alston appears likely to make clear that austerity has been a political choice and highlight how Nicola Sturgeon, the Scottish first minister, told him the devolved government in Edinburgh has been spending £125m to mitigate the effects of cuts.

In 1976, the UK signed a UN treaty agreeing to protect economic and social rights, but has proved hostile to enshrining it in law.

Alston described himself as a “fanatic” who believes economic and social rights “are of the utmost importance”. If they were incorporated into law, as they are in Sweden and Germany, it would require a radical rebalancing of public service finance, probably in favour of more taxes and higher spending.

He said there would be “hilarity or disbelief” in government if he suggested incorporation into law, so he is unlikely to push for that.

He will issue a short report of about 10 pages on Friday before making a fuller report to the UN’s human rights council in Geneva in June.