Generations of Africans face incestuous rape and discrimination in country that is west's ally against al-Qaida, says rights expert

Black Mauritanians are still subject to slavery-like practices, including sexual violence and discrimination, a UN human rights expert has said.

The UN special rapporteur on racism, Mutuma Ruteere, told the Guardian that generations of people, particularly women and girls, were still living with families in a "slavery-like" relationship, and were being forced into sex with male relatives, in some cases with their fathers.

"You have situations where people still live with and are working for certain families, and where women are forced to have sexual relations with family members – fathers and sons," said Ruteere, speaking from Kenya. "And there are situations where children, particularly the girls who are the products of those relations, are then forced to have sexual relations with the same family members."

"This kind of relationship is going on over generations. There is a lot of sexual violence against these women and girls, I met individuals who are subjected to this. It's a situation that is slavery-like."

The comments by the Kenyan human rights veteran are among the most outspoken condemnation of events in Mauritania by the international community in recent years.

A predominantly Muslim former French colony on the western coast of the Sahara desert, Mauritania is seen by western powers as an important ally in the fight against terrorist groups such as al-Qaida in the Islamic Maghreb, which have been active in the country, crossing porous desert borders with neighbouring Mali.

Critics say Mauritania's geopolitical role has led to human rights violations being overlooked in the nation, which is divided between Arab-Berber and black African ethnic groups, some of whom were traditionally enslaved. Enslavement was not made a criminal offence in Mauritania until 2007, after years of official denials that the practice still existed.

Anti-slavery groups claim they are regularly harassed by the authorities, and one organisation said that during Ruteere's visit to Kaédi, a town in southern Mauritania, it was obstructed from introducing victims of slavery to the UN delegation.

"We went to Kaédi to accompany the rapporteur and to introduce him to victims of slavery so that he could see for himself," said Balla Touré, spokesperson for the Initiative for the Resurgence of Abolitionism in Mauritania (IRA-Mauritania).

"The authorities blocked us from hotel rooms we had reserved at the hotel in Kaédi so that we could meet with Mr Ruteere. We were refused access to our rooms. Government officials also prepared false victims for him to meet with, who told him that things have really changed and that Mauritania is no longer racist. These things are completely false.

"And officials physically tried to prevent real victims from entering the room to meet with the rapporteur. They vetted each one, and told some they could enter, and others they could not."

The Mauritanian government did not respond when asked about the IRA's allegations, but denied that slavery exists or that it had harassed anti-slavery campaigners.

It said it had strengthened legal and institutional protection against slavery and racism, including the enactment of the 2007 law, and by co-operating with the UN human rights system, establishing a national human rights commission, and amending the constitution to acknowledge Mauritania's ethno-cultural diversity.

But civil rights groups say slavery and racial discrimination are still entrenched in Mauritania and accuse the government of a cover-up. They point to cases such as that of Omar Djibi Sow, 45, who escaped in July after 40 years of slavery, during which he was made to herd camels for his "master".

The Guardian has seen details of two further cases pending before the courts, including one in which a former colonel is accused of enslaving a woman and her son, subjecting them to "psychological pain" and "inhuman and immoral practices".

In another case, a man and his son admitted to enslaving a woman and nine of her children, saying that they had inherited the family.

"These are sad stories that are common in Mauritania," said anti-slavery activist Saidou Wane. "To say slavery in Mauritania is over is just a lie. There are cases pending in the courts, and groups like the IRA are constantly finding new examples of slavery.

"If slavery ended, and the government has nothing to hide, then why doesn't it allow a proper investigation? Why does it harass groups like the IRA which are doing just that?"

Although Ruteere praised the 2007 law for criminalising the practice of slavery, he agreed that the courts were not delivering justice for black Mauritanians.

"There are several cases that have been brought by individuals who are living under slavery-like conditions, and either the cases took too long, or the sentences are too light, the individuals are being released after a short time even after a conviction," said Ruteere. "People feel that the justice system is not working for the victims."

It is not the first time the UN has made damning findings against the Mauritanian authorities on racism.

In 2009, UN special rapporteur on slavery Gulnara Shahinian also visited Mauritania and reported having met victims of the practice.

"Even though the UN acknowledges 'slavery-like practices', it is frustrating that they will not come out and just speak the truth, that slavery exists in Mauritania," said Wane. "No one wants to upset the government, everybody is being politically correct. But the people know what is really happening, and little by little they are starting to rise up against it."