Nearly all of the defendants were themselves Nigerian, in the latest case to highlight the growing use of African migrants in the European sex trade.

They include one of Europe's most wanted women, Jessica Edosomwan, accused of acting as a France-based “madam” to women recruited mainly in Nigeria's southern Edo State.

Edosomwan was tried in absentia.

Nigeria was the main country of origin for the tens of thousands of migrants who crossed the Mediterranean to Europe by boat in 2016 and 2017.

Many were women and girls lured to Europe with false promises of jobs as hairdressers or seamstresses, only to find themselves selling sex to repay their smugglers.

Seventeen women filed complaints against the defendants but none of the victims attended the trial, with the exception of one former sex worker who found herself in the dock for luring another woman into the trade.

The accused had faced up to 10 years' imprisonment on charges including human trafficking, pimping, money laundering and helping people live illegally in France.

Prosecutors estimated that the victims, aged 17 to 38, made up to $166 000 a month for the syndicate by selling sex in vans parked by the side of the road for as little as 10 euros.

A French mechanic who looked after the vans was among the 24 defendants.

Last year, 15 members of a Paris-based, female-led pimping ring known as the “Authentic Sisters” – many themselves former trafficking victims – were jailed for up to 11 years for forcing girls into slavery in France.

Similar gangs have also been dismantled in Italy and Britain.

The UN estimates that 80 percent of young Nigerian women arriving in Italy – usually their first port of call in Europe – are already in the clutches of prostitution networks, or quickly fall under their control.

Most of the women come from Nigeria's Benin City, a human trafficking hotbed.

Many told investigators they had taken part in “juju” or black magic rituals before leaving Nigeria, during which they had to promise to repay the money for their passage to Europe.