Mauritania's president dissolved the National Assembly on Monday and announced legislative, regional and municipal elections for May 13, the Interior Minister said.
The parliamentary term was meant to end in August but an agreement was struck to hold early elections to avoid the rainy season, when some regions can become difficult to access.
Interior Minister Mohamed Ahmed Ould Mohamed Lemine made the announcement after an exceptional meeting of the council of ministers.
The number of members of parliament will also increase to 176 from 157, according to the official news agency.
President Mohamed Ould Cheikh El Ghazouani's party held a comfortable majority in the now-dissolved assembly, while the opposition is divided.
Mauritania's former president Mohamed Ould Abdel Aziz is currently on trial, together with two former prime ministers and several former ministers and businessmen, for allegedly abusing their power to amass huge fortunes.
The trial will resume on March 20, the prosecutor's office told AFP.