(NewsNation) — A poverty expert at the United Nations is calling on the CEOs of three major corporations to address allegations that their low salaries are forcing workers to rely on government assistance to survive.

Olivier De Schutter, the U.N. Special Rapporteur on extreme poverty and human rights, sent letters to the leaders of Amazon, Walmart and DoorDash, saying in a Tuesday news release that the “multi-billion dollar companies should be setting the standard for working conditions and wages, not violating the human rights of their workers by failing to pay them a decent wage.”

“I am extremely disturbed that workers in some of the world’s most profitable companies — in one of the richest countries on earth — are struggling to afford to eat or pay their rent,” De Schutter added.

The UN expert pointed to a 2020 government report naming all three companies among the top employers of people receiving government medical and food aid.

Amazon said in a response to De Schutter’s letter that the company invested $1.3 billion in wage increases in the U.S. this year, bumping average hourly pay to $20.50 per hour. Amazon noted that a full-time worker making the starting pay of $17 an hour would gross $2,944 per month, “likely disqualifying them for SNAP or Medicaid.”

Walmart said in its response that its average starting wage is more than $15.25 per hour, and the average hourly wage for all associates is more than $17 per hour.

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“While we appreciate the intention behind your letter, we take issue with the multiple factual inaccuracies and mischaracterizations of our workforce that are reinforced by the citation of outdated studies, articles and anecdotes,” the company said.

DoorDash has not yet replied.

De Schutter’s letters to the companies also zeroed in on independent contractor policies and alleged union-busting.

“It appears that the US is turning a blind eye to the union-busting activities of its most powerful corporations, allowing them to steamroll workers into accepting poverty wages while corporate revenues soar,” De Schutter said in the release.

Amazon and Walmart both denied the allegations.