A Chadian minister, who served as the country's premier from 2013-16 was arrested on Sunday over fraud allegations, a police spokesperson told AFP.
Kalzeube Pahimi Deubet was detained following a complaint from the state inspectorate general for fraud, the spokesperson said.
Currently secretary-general of the presidency, his post involves coordinating government action. As well as the premiership, he has also held a number of ministerial positions.
Chad President Idriss Deby Itno, who has governed the poor, oil-rich state since 1990, last year vowed to crack down on entrenched graft.
The landlocked country has a history of political violence and corruption. It was ranked 165th out of 180 countries in Transparency International's 2018 Corruption Perceptions Index.