Nothing illustrates the moral schizophrenia of our age than two events in the United States this week. Today marks the anniversary of the effective emancipation of African-American slaves in 1865. The US Senate has passed a resolution formally apologising for the "fundamental injustice, cruelty, brutality, and inhumanity of slavery".

But on Tuesday, the State Department released its Trafficking in Persons Report 2009. This dismal document estimates that there are still over 12.3 million adults and children in forced labor, bonded labor, and commercial sexual servitude at any given time in the world. About 1.4 million of these are victims of commercial sexual servitude. Even President Obama has acknowledged that slavery still exists in the US: "Sadly, there are thousands who are trapped in various forms of enslavement, here in our country… oftentimes young women who are caught up in prostitution... It is a debasement of our common humanity".

According to John R. Miller, former US ambassador at large on modern day slavery, as many as 17,500 slaves may enter the United States every year. As elsewhere, contemporary American slaves work in brothels, massage parlors, and other sex businesses, or as domestic servants.

The abolition of transatlantic slave trade last century made slavery illegal, yet it did not end it. Rather, it has evolved into human trafficking. According to the head of America’s Office to Monitor and Combat Trafficking in Persons, Luis CdeBaca, it nets human traffickers, worldwide, about US$31 billion in profit a year. An anti-trafficking organisation, the Polaris Project, calls it "fastest growing criminal industry in the world".

And it is this, rather than glass ceilings or "reproductive rights", or flexible working hours, which must be the biggest feminist issue of our time. Miller says: "Sex servitude -- of which 80 percent are women or girls -- is one of the largest discrete category of trafficked humans".

In fact, one of the major drivers of the flow of women and children slaves from underdeveloped countries to developed countries is the increasing demand for commercial sex. Legalised prostitution in Europe and the US is supposed to make it "safer" by keeping prostitutes off the streets and protecting them from exploitation by criminal gangs. Experiments such as the Dutch "red light district" or "tolerance zone" where prostitutes are concentrated and the granting of brothel licenses by Australia and Germany, however, have failed. On the contrary, they have aided the expansion of sex industry.

But the West seems blind to the fact that permissive attitudes are fuelling modern slavery. Significantly, the State Department’s report this week had a few recommendations for decreasing human trafficking in the Netherlands – like continuing "anti-trafficking awareness initiatives aimed at educating clients of the commercial sex trade". Nothing at all about criminalising, or even discouraging, the sex trade.

Sex workers are hard to recruit in prosperous welfare states, because it is a shameful profession and because there is always an alternative. A 2008 poll in the UK showed that it was young people who were the most opposed to prostitution – 64 percent of youths said that paying for sex was "unacceptable" and 69 percent believed that selling sex was "unacceptable". About 60 percent would have felt ashamed if they found out a family member was working as a prostitute. One fortunate consequence of Europe’s generous social welfare system is that it helps to keep women out of prostitution

As a result, the sex industry looks overseas. According to the US State Department, millions of people are trafficked yearly across European borders. In Amsterdam, Netherlands, 80 percent of prostitutes are foreigners, and 70 percent have no immigration papers, suggesting that they were trafficked.

Contrary to what most people in Europe and the US read in their media, Africa is not a hell-hole. However, poverty and insecurity often encourage many Africans to migrate to Europe. Traffickers exploit this desire.

In Nigeria, where I live, there are appalling cases. The southeastern city of Edo has the highest number of girls working as prostitutes in Europe. A survey a few years ago found that one in three young women in Edo had received offers to go to Europe. An estimated 20,000 Nigerian women are working as prostitutes in Italy and almost all of them come from Edo. Some of them prosper and build mansions back in their villages.

To stem the tide, European countries impose stringent visa requirements, but these are circumvented by traffickers with the connivance of corrupt government officials. Criminal syndicates obtain false papers for flights to Europe or border permits for land trips. The land trips are often harrowing. A Guinean official told an anti-trafficking website that agents usually take the girls to Guinea via the Republic of Mali where false Guinean passports are procured for them using fictitious names. The girls are then returned to Mali where they are sold to other syndicates that transport them through long and torturous land routes. They travel by foot and by car; through Morocco, through Gibraltar, through Spain and then to Italy or other European countries.

Upon arrival, the traffickers confiscate the girls’ papers for "safekeeping" until they pay back fictitious "travel expenses" which often run into hundred of thousand of dollars. The slaves are thus bound for years, toiling to pay these debts. Not knowing anyone, and having no papers, they have no choice. They cannot find legitimate work and in a strange country without language skills they cannot escape.

There are even latter-day Timbuktus where buyers haggle over human flesh. Nazir Afzal, of the Crown Prosecution Service told the BBC in 2006: " We are now seeing 'slave auctions' being held in public places at airports where brothel keepers are bidding for women destined for prostitution." One took place outside a coffee shop at Gatwick Airport, and others at Heathrow and Stansted.

Intimidation and violence are common. The traffickers make the girls take oaths on pain of death. One slave rescued by anti-trafficking agencies said: "They promised me a job as a waitress, but when I arrived here they forced me to work as a prostitute. They told me I owed them a lot of money for my trip, and they took my passport and said they would hurt my family back home if I did not do what they wanted."

If traffickers suspect that a slave is trying to escape they may kill her. In the early 1990s, the number of foreign women murdered in Italy - mainly Albanians and Nigerians - accounted for 6 percent of all murders. Since then, the figure has risen as high as 23 percent.

Sex-slave trafficking in Africa is a difficult to fight because its impoverished victims want to go abroad for a better life -- though normally not as a prostitute. In addition, most of them are afraid of testifying in court against their traffickers for fear of reprisals against relatives back home. That is why the National Agency for the Prohibition of Traffic in Persons and other related Matters, an anti-trafficking agency based in the Nigerian capital Abuja, wants a comprehensive witness protection law.

Slavery is a difficult issue to solve, but the rise of 21st century slavery is partly due to Western attitudes towards sexual morality. Progressive social legislation accepts rather than challenges prostitution. Europe and the US need a new Wilberforce to convince people that private vice has public consequences. Only then will women slaves be able to shake off the shackles of their degradation.

Chinwuba Iyizoba is an electrical engineer in Enugu, Nigeria