The deportation of thousands of migrants from the US to third countries has set off a “cascade of human rights violations” that could have “deadly” consequences, two dozen UN human rights experts have warned.

Since Donald Trump returned to power in 2025, the US government has been offering millions of dollars to foreign governments to take in migrants, including refugees and asylum seekers, with no ties to their countries. Deals have been struck with 35 nations, nearly a third of them in Africa.

About 20,000 people have been taken by bus to Mexico, according to Refugees International and Human Rights First. More than 5,000 others have been put on flights to countries in Africa, Latin America, the Caribbean and central Asia.

On Monday, 24 experts who advise the UN Human Rights Council – backed by a special rapporteur for the African Commission – said they had contacted the US and each of the 35 countries to express their concerns and call for an immediate halt to the policy.

“The harms caused by this US government scheme are no longer hypothetical,” they said in a joint statement. “The arrangements are triggering a cascade of human rights violations. For migrants in situations of particular vulnerability, the consequences can be deadly.”

Those being banished to countries where they had no connections faced an increased risk of torture and ill-treatment, as well as enforced disappearances, they noted.

“These migrants are being transferred to countries or territories with which they have no ties, which can be a traumatising and isolating experience that compounds harms already suffered which triggered their fleeing to the US in the first place. Others are sent to places where they risk further violence or discrimination based on gender, sexual orientation, gender identity or human rights advocacy.”

The Trump administration says deportations are focused on removing criminals from the US. However, an investigation by the Guardian as part of a consortium of journalists coordinated by the Forbidden Stories network uncovered the ordeals of some who have been deported. They included an Iranian woman who had sought safety in the US after protesting against the regime and a gay man who had fled Ghana after he was outed, then hunted, by members of his own family.

On Monday, the UN-linked experts warned that deportations to unfamiliar countries could leave people vulnerable to other violations, from trafficking to slavery.

In some cases, the countries that have struck deals with the US are engulfed in conflict, meaning US arrivals were turning up in places where people were already grappling with displacement, starvation and debilitating poverty. These countries, the statement noted, “lack the capacity to protect the rights of migrants sent there by wealthy nations seeking to shirk their international obligations”.

Human rights lawyers say the deportations allow the US administration to skirt around its legal obligations because US law does not allow people to be sent back to countries where they are likely to be persecuted. Instead, the Department of Homeland Security has been deporting migrants, including asylum seekers, to third countries. From there, they are often moved on to home countries they had fled.

Monday’s statement pointed to the severe impact this could have on people who were already vulnerable: “What is at stake is not merely migration policy, but the lives, safety, dignity and rights of people who may already have endured grave harm and who, in many cases, are fleeing life-threatening persecution and violence in their home countries.”

It was the first comprehensive statement of its kind, according to Beatrice Njeri of the Global Strategic Litigation Council, which has represented people expelled from the US to third countries.

“It comes at a very important point in time when we are continuing to see extreme human rights violations that are super horrific,” she said, citing two men expelled to Equatorial Guinea who had been bound, fitted with bags over their heads, beaten and pushed down a flight of stairs.

Njeri, who works as the organisation’s regional litigator for Africa, said the African states involved in the scheme had paid little attention to any of the pleas, litigation and advocacy aimed at halting these arrangements. “So, it has felt like we’re screaming into a void. And we hope that this statement will contribute to trying to hold these states accountable.”

She said some EU countries were ramping up their own calls for the creation of offshore centres for migrants. “This is a good warning to them not to follow suit,” she said. “European states now clearly know how African states are implementing the agreements, violating people’s rights and offering no redress. And so they have no excuse.”