“Does anybody need a digger? This is a digger, a big strong man, he’ll dig,” the auctioneer says in grainy mobile phone footage, gesturing to one of the two tall, silent young men next to him.

“What am I bid, what am I bid?”

The two men were sold together for a total of $400 (£296).

The world has been shocked by the release of a CNN investigation into the slave trade thriving in the lawlessness of post-Gaddafi Libya.

Smugglers in Libya sell migrants as slaves

It is estimated hundreds of sub-Saharan Africans travelling to Libya in the hopes of getting on a boat across the Mediterranean to a better life in Europe are being sold by smugglers each week – either into lives of manual or sex slavery or ransomed to their families, passed between militia groups.

The UN is trying to decide if crimes against humanity charges can be brought against perpetrators. Protests erupted in Paris and several other cities and the Libyan government – only in control of around half the country – has promised an investigation.

“It is now clear that slavery is an outrageous reality in Libya. The auctions are reminiscent of one of the darkest chapters in human history, when millions of Africans were uprooted, enslaved, trafficked and auctioned to the highest bidder,” a statement from a group of UN human rights experts said.

Many Libyan activists and non-governmental organisations have been trying to raise the alarm about the worsening situation in Libya for months.

The UN’s International Organisation for Migration (IOM) released a report in April this year warning that sub-Saharan Africans who travelled north to Libya were routinely facing detention in squalid conditions, rapes, beatings and being sold into slavery.

In pictures: A day of refugee rescues in the Mediterranean Sea Show all 7 1 /7 In pictures: A day of refugee rescues in the Mediterranean Sea In pictures: A day of refugee rescues in the Mediterranean Sea A baby being taken on to MSF's Bourbon Argos ship from a boat carrying 130 migrants and refugees Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A refugee boat carrying 101 people being rescued by MSF's Bourbon Argos Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A refugee boat carrying 101 people being rescued by MSF's Bourbon Argos all images by Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A baby among refugees on a boat carrying 185 people off the coast of Libya Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea Migrants and refugees sleeping after being rescued by MSF's Bourbon Argos ship Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A crew from MSF's Bourbon Argos ship rescuing a boat carrying 130 migrants and refugees off the coast of Libya, at sunrise Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A woman in a stretcher being lifted onto MSF's Bourbon Argos ship from a boat carrying 130 migrants and refugees off the coast of Libya Lizzie Dearden

“The humanitarian crisis of migrants trying to reach Europe is well documented, and it is a story the Libyan authorities want to be told,” said photographer Narciso Contreras, who was one of the first foreigners to capture the extent of the modern day Libyan slave market.

“But that vast market trading in human beings is largely undocumented,” he added.

That has changed with the release of the latest footage. How to best address the problem is not clear.

But perversely, at this point, the people who know the least about the perils that await migrants from Nigeria, Chad, Sudan and Niger when they finally arrive in Libya are the migrants themselves.

Several activists on the ground in Libya who The Independent spoke to said that slavery, ransoms and detentions of African migrants are not new. And yet, more and more people arrive every day, determined to believe that a better life awaits them elsewhere.

“I’ve never met an African in Libya who knew what could happen to him during his journey to Libya,” Misrata-based journalist Mohamed Lagha told The Independent.

“But I have met many migrants who told me that they paid to get out of prisons or detention centres, and that militias forced them to work for free.”

Some of those who do hear what could await them in Libya refuse to believe the stories, as BBC reporter Benjamin Zand found on the migrant trail through West and North Africa recently.

“In life there are always risks,” two well-dressed women in Niger told him when he tried to warn them. “We will be amongst the successful ones.”

As nightmare-ish as the situation in Libya is, it could yet get worse.

The trade in human beings has risen sharpy since the Italian government began paying Libyan militant groups and smugglers to stem the flow of migrants over the sea earlier this year.

Fewer people are now making it to the shores of Lampedusa and southern Italy as countless legions more remain trapped in militia detention centres in Libya.

Libyan Coast Guard puts refugees and rescuers in danger during rescue operation at sea

But the death rate in the long and treacherous ocean journey from North Africa has now doubled.

At least 2,550 refugees and migrants died between the beginning of the year and 13 September 2017 compared to 3,262 from the same period in 2016, the IOM reported.

That figure represents a drop of 22 per cent – but since 57 per cent fewer people actually make it to Europe now, that means the rate has rocketed to one death in every 50 people who actually make it to Italy’s shores.

How to best address the complex trafficking web remains unclear.

The influx of Italian money has also poured fuel on the fire of Libya’s civil war, paying for weapons and militia mens’ salaries.

Until life at home is attractive, and escaping poverty is possible, thousands more Africans will journey across the continent to Libya.

There is no easy fix for the situation. Growing talk of certain mercenary solutions – such as Blackwater founder Erik Prince’s privatisation plans – do not bode well for a workable solution.

Mr Prince told Italian newspaper Corriere della Sera that his company, Frontier Services Group, could stop, detain, house and “repatriate” hundreds of thousands of African migrants who are seeking a path to Europe through Libya.

He said he could do so for a “fraction” of what the EU is spending on boats to stop vessels in the Mediterranean, and that his plan would be more “humane and professional” .

“The traffic of human beings from Sudan, Chad, Niger is an industrial process,” he said. “To stop it, you have to create a Libyan border police along the southern border.”

Activist groups are pessimistic about genuine action being taken to solve the crisis.