The fear is there, day and night, said Mamadou from Chad, who asked that DW not use his full name for fear of reprisals, recounting what happened to him earlier this month after he failed to reach the Italian island of Lampedusa with the help of human traffickers.

"The Tunisian Coast Guard officers took our cell phones and our money, then they drove us to the Libyan border where they stripped us and left us alone," he told DW from his hiding place: An olive grove near Tunisia's port city of Sfax. He said he had walked around 240 kilometers (ca. 150 miles) through the desert to get there.

Hiding in an olive grove

The olive grove has become a notorious hiding place for around 80,000 sub-Saharan migrants waiting for a chance to cross the Mediterranean Sea so that they can get to Europe.

Lauren Seibert, a researcher at Human Rights Watch who focuses on refugee and migrant rights, said that what Mamadou and others had experienced was "an unlawful collective expulsion, or what people are calling 'desert dumps.'" 

Algeria, Libya and Mauritania had been "practising collective expulsions for many years," she told DW, but in Tunisia it was a more recent phenomenon had appeared to become systematic since last year.

That view was echoed by an expert on Tunisian migration who spoke to DW on condition of anonymity: "In the past years, there have been a handful of cases, usually when smuggler boats from Libya were intercepted by Tunisian authorities," he said.

"Now, expulsions seem to be more systematized, in part they involve urban detentions in places like Sfax and Zarzis and they also entail a shift in how migrants intercepted at sea are handled," he added. 

Earlier this month,  Lighthouse Reports, an investigative news organization that collaborated with several international media outlets published a report about the increase of so-called "desert dumps."

After a year-long investigation, it concluded that the Tunisian National Guard was at the center of these operations, with much of the finances coming from European countries.

Incentivized migration curbing

Since last year, the EU has entered migration partnerships with Egypt, Morocco, Mauritania and Tunisia, deals that include funding specifically meant to be used to curb migration to Europe. 

For many observers, the recent developments in Tunisia's migration policy is especially worrying, since Tunisia has become a popular departure point for migrants from across Africa hoping to get to Europe. 

The country had capped visa requirements in 2015, and it was widely known that the country needed for cheap labor in the unofficial sector, which made it a good stopping place for people to raise the funds to get across the Mediterranean.

In the past decade, the port city of Sfax, which is less than 150 kilometers (90 miles) from Lampedusa, has become a major hub for human trafficking, something that was more or less tolerated by the Tunisian authorities.

But in February 2023, Tunisian President Kais Saied launched a new crackdown on migrants after claiming that sub-Saharan migrants entering the country were deliberately changing the demographic structure of Tunisia. He said that this threatened to transform Tunisia into an "African" country instead of an "Arab-Muslim" one.

This was followed by a nationwide police operation that was in part supported by the Tunisian population, with many sub-Saharan families being harassed on the streets, evicted from their homes and arbitrarily detained.

However, after international condemnation and some minor local demonstrations, Kais Saied visited Sfax in an attempt to calm the situation.  

In July last year, European Commission President Ursula von der Leyen offered a partnership package to Tunisia worth more than €1 billion ($1.08 billion), consisting of €900 million plus €150 million in immediate budget assistance, and a further €105 million for border management and anti-smuggling activities.

Though Kais Saied has repeatedly insisted that Tunisia would become neither a "center nor a crossing point for sub-Saharans," human rights activists say that illegal collective expulsions are soaring. "The increasing EU funding dedicated to migration control only encourages these collective expulsions, which are contrary to regional and international law," HRW's Seibert told DW.

According to the news agency AFP, the EU did not respond explicitly to the allegations by Lighthouse Reports, though EU Commission spokesperson Ana Pisonero said that "sometimes the situation is challenging in our partner countries... (but they) remain sovereign states and they continue to be in control of their national forces."

For Seibert, these are empty words. "In fact there is a clear line that can be drawn between EU funding and the continuation of these practises," she said.

Systematic expulsions

When Tunisia first deported around 1,200 migrants to the border with Libya in May 2023, "it catalyzed a humanitarian crisis, which left several migrants, including children, dead, and it also drove a political crisis between Libya and Tunisia," the migration expert told DW on condition of anonymity. 

However, following an international outcry, large-scale deportations stopped in July, only to be resumed in September, when Tunisian authorities once more started detaining large numbers of people.

"Since then, some of the transportation goes to the Algerian border, where there's a lot of tension with Algerian border forces, others to the Libyan border," the observer said.

"Although Tunisia's current expulsions to the Libyan border don't breed a humanitarian crisis as migrants are being pretty quickly picked up by Libyans, they are nevertheless brought to detention centers where they face the risk of abuse and extortion."  

Tarak Guizani contributed to this report from Tunisia.