The incarceration comes days after the former leader refused to continue to report to police when he was placed under house arrest.
Former Mauritanian President Mohamed Ould Abdel Aziz has been jailed after a judge investigating corruption ordered his jail time.
The ex-leader says he is being persecuted in an attempt to keep him out of politics but has vowed he will not go into exile.
A prosecutor speaking on condition of anonymity and the spokesperson for the former president’s party, Djibril Ould Bilal, confirmed his detention on Tuesday without giving the reason.
Aziz has appeared twice before a magistrate investigating the case since the charges, including money laundering, were laid in March.
The move comes days after the former leader refused to continue to report to police after being placed under house arrest.
Aziz led the conservative West African state from 2008 to mid-2019, when he was replaced by his former right-hand man and former defense minister Mohamed Ould Cheikh El Ghazouani.
Oil revenue survey
Aziz joined a small opposition party, the Ribat National, in April in an attempt to save his political career after being kicked out of the ruling Union for the Republic (UPR) party he founded.
The 64-year-old former general, who came to power in a coup, already had to report to the police three times a week and seek approval before leaving the capital.
The charges followed a year-long investigation launched by Parliament into the management of oil revenues, the sale of state property, the liquidation of a state-owned food supply company and the operations of a Chinese peach.
A public prosecutor involved in the investigation in March said cash and assets worth around 96 million euros ($ 115 million) were seized.