Mauritanian police freed 42 people on Sunday who were arrested after a protest demanding justice for victims of civil unrest between 1989 and 1991, one of the rally organisers said.
Among other demands, the widows and families of victims want the repeal of an amnesty law that shields alleged perpetrators of crimes committed during two years of strife between the West African state's black population and Berber-Arab Moors.
One of the most notorious incidents was the 1990 hanging of 28 black Mauritanian soldiers accused of plotting a coup.
A 1993 amnesty law means nobody was ever tried for the crimes but the families were compensated.
Forty people were arrested in the capital Nouakchott at a demonstration by widows and relatives of victims of the unrest, according to Lalla Aicha of local rights NGO FONAD.
A further two people were arrested in the southern town of Bababe, on the border with Senegal, she said.
A police officer, who requested anonymity, confirmed the arrests to AFP and explained that the government had not authorised the protests.
One of the protest organisers, Dia Alassane, said all the detainees were freed on Sunday.
Former President Mohamed Ould Abdel Aziz, who governed between 2008 and 2019, apologised for the events of 1989-1991 but many rights groups continue to demand accountability.
