613 of them traveled from their native Niger to neighboring Libya, where many of them planned to reach Europe via the Mediterranean Sea, a journey that thousands of people from sub-Saharan Africa strive to make each year.

But late last month, Libyan authorities deported the men in one of the country’s biggest expulsions in years. The mass deportation is part of a common pattern: North African governments, funded by the European Union to tackle migration, are using brutal tactics to prevent migrants from sub-Saharan Africa from making their way to Europe.

613 of them arrived in the Niger city closest to the Libyan border on January 3, ragged and hungry, some barefoot and sick after months of captivity and days of travel across the Sahara. The two men died shortly after arriving in Niger.

“I lived through hell,” said Salmana Issoufou, one of the men. Mr. Issoufou, 18, said Libyan prison guards beat him with wires and guns during his eight-month detention.

As anti-migrant sentiment rises across Europe, from France to Germany and Hungary, North African governments are cracking down on sub-Saharan Africans trying to reach the continent on a scale not seen in years. The EU has signed bilateral agreements with Tunisia, Morocco, Libya and Mauritania that include financial support for curbing migrant flows.

The strategy seems to be working: illegal border crossings dropped sharply in 2024, according to recent data data from the border agency of the European Union, Frontex.

But rights groups say the methods used to prevent sub-Saharan migrants from traveling to Europe include well-documented human rights abuses, such as the so-called desert dumps. Migrants were abandoned in the Sahara without food and water, or held in North African prisons where they face each other whippingsexual violence and starvation.

Since Tunisia made a deal with the European Union in 2023, it is thrown more than 12,000 people, including children and pregnant women, to abandoned areas of Libya, according to the United Nations. Last year, the EU signed a similar agreement with Mauritania.

In Libya, the European Union financed the country’s coast guard, for which it is accused firing live ammunition during interception at sea and handing over migrants to violent militias.

The investigation conducted by a a consortium of newspaper houses last year it showed that North African security forces used vehicles and intelligence provided by EU countries to arrest migrants or transport them to desert areas.

The 613 men sent back to Niger this month had been detained in Libya since at least last fall, according to regional officials in Niger, who escorted them across the border to Dirkou, a Niger city about 400 kilometers south of Libya.

Two men died in Dirkou, according to Abba Tchéké, a social worker who helped the men there and who works for Alarm Phone Sahara, a nonprofit that rescues migrants stranded in the desert.

The men reached Agadez, the largest city in the north of Niger and a major transit hub for migrantslast week. They were exhausted and dehydrated, and some had skin wounds and broken limbs. Half a dozen men who were deported said in interviews with The New York Times that they were mistreated by Libyan authorities.

Adamou Harouna, 36, said prison guards burned him with plastic while he was in custody.

The mass deportations from Libya echo similar moves from Algeria, which shares a 580-mile border with Niger and deported more than 31,000 people last year, the highest number in years, according to Phone alarm Sahara.

Algerian authorities are abandoning migrants at the border with Niger, forcing them to walk for hours through the desert before reaching the nearest town. Migrants also face beatings and of physical violence in Algerian prisons. (The European Union does not have a migration agreement with Algeria.)

While deportations from Libya to Niger have so far been smaller than from Algeria, recent mass deportations have raised concerns about a potential increase. Last year hundreds of African citizens were forcibly returned from Libya to Chad, Egypt, Sudan and Tunisia, according to the United Nations.

In Africa, the United Nations International Organization for Migration returns deported migrants to their homelands. In Niger, the organization transports people abandoned in border areas back to Agadez and later to their home countries on planes that depart several times a week.

For men from Nigeria, the organization organized buses. Mr. Issoufou, 18, said he would stay in Niger. Mr Harouna said he planned to travel back to Libya as soon as possible.

Ibrahim Manzo Diallo contributed reporting from Niamey, Niger, Saikou Jammeh from Dakar, Senegal, and Jenny Gross from London.