A Mauritanian court on Thursday upheld a two-year prison sentence against three anti-slavery activists who were arrested during a protest against bondage in the west African nation.
Biram Ould Dah Ould Abeid, runner-up in the 2014 presidential elections and head of the Initiative for the Resurgence of the Abolitionist Movement (IRA), was jailed in January alongside two other activists.
"The (appeals) court upheld the sentences," a judicial source told AFP. The failure of the activists' appeal was confirmed by a spokesman for the IRA.
The two others convicted were Bilal Ramdane, an assistant to Ould Abeid, and Djiby Sow, a civic and cultural rights campaigner.
Sow has however since been released on parole due to health problems.
"This is a step backwards for freedom in our country, an example of judicial authorities submissiveness to executive orders," said defense lawyer Brahim Ould Ebetty, who boycotted the hearing along with his clients.
He slammed a "parody of justice" just two weeks after Mauritania adopted a new law to crack down on slavery which activists say is widespread in the west African nation despite being criminalised in 2007.
The new law declared slavery a "crime against humanity", criminalises a raft of new forms of slavery such as forced marriage, and doubles maximum prison terms to 20 years.
Slavery is deeply entrenched in the vast, largely desert nation where light-skinned Berber Arab Moors enslaved local black populations after settling in Mauritania centuries ago.
Slave status is also often passed on from generation to generation, said the Australia-based Walk Free Movement which estimated in its 2014 Global Slavery Index that there were 156,000 slaves in Mauritania, or some four percent of the population.
The country was the last in the world to abolish slavery, in 1981, and since 2007 its practice has been officially designated a crime.
However activists accused government of failing to implement the laws.
Sarah Mathewson of Anti-Slavery International told AFP only one person had ever been convicted under the old law, and many cases watered down to "unpaid labour".
The three activists were arrested in November 2014 while protesting slavery in a move Amnesty International said was "politically motivated".
They were found guilty of "belonging to an illegal organisation, leading an unauthorised rally, and violence against the police."
Mauritanian authorities have accused the IRA of spreading "racist propaganda"
"We feel that there is hypocrisy because (authorities) seem more intent on prosecuting anti-slavery activists than applying the existing law which was perfectly valid and could have been very effective except there was resistance to enforcing it," said Mathewson.