An appeal court has confirmed that the main rival of President Maaouiya Ould Taya will be stripped of his political rights for five years.
Meanwhile, the government is speeding up preparations for the trial of 125 soldiers accused of taking part in a failed coup last year.
Justice Ministry sources said Ould Taya was anxious to bring them to court before the first anniversary of the uprising, on 8 June.
On Tuesday, the supreme court upheld a verdict that Mohamed Khouna Ould Haidalla, the main challenger to to Ould Taya in last November’s presidential election, was guilty of planning a coup to seize power immediately after the poll.
Ould Haidallah, a former military president who was deposed by Ould Taya in 1984, was served with a five-year suspended prison sentence on 28 December that automatically strips him of all his political and civil rights for five years.
Earlier this month, the government rejected an application by supporters of Ould Haidalla to legalise a new opposition party. It included several prominent Islamic radicals.
Haidallah’s defence lawyer, Brahima Ould Ebetty, told IRIN on Wednesday that the government had engineered and manipulated the trial simply to remove Ould Haidalla from the political scene.
“Collective and individual rights remain threatened in this country which claims to live by the rule of law, but where the necessary independence of the judiciary is just a theory that is far removed from the reality on the ground,” Ebetty said.
The Pan-African human rights group RADDHO expressed its grave concern at the Supreme Court’s decision to uphold Ould Haidalla’s conviction.
The Dakar-based organisation said the ruling “sums up the political climate in Mauritania.”
It urged the international community to encourage a dialogue between the Mauritanian opposition and those in power.
Ould Taya has ruled the desert state of three million people with an iron hand for the past 20 years, but he was very nearly unseated by last year’s coup attempt, which led to two days of heavy fighting in the capital Nouakchott.
Although many of those suspected of taking part in the uprising were subsequently arrested, the leader of the coup plot, Saleh Ould Hanenna, remains on the loose.
Government officials believe he is holed up with a handful of supporters near the lawless border with Mali, an area dominated by independent tribal chieftans, bandits and smugglers.
Military sources said several relatives and clansmen of Ould Hannena were recently rounded up for questioning, but most had since been released.
Human rights activists in Mauritania have warned the disparities between rich and poor are likely to be magnified when the country’s first offshore oilfield comes on stream in about two years’ time.