Government candidate and frontrunner Mohamed Ould Ghazouani has won an absolute majority in the first round of Mauritania's presidential election, with nearly all votes counted, the Independent National Electoral Commission (CENI) said on Sunday.  

With counting completed in 3,729 of a total of 3,861 polling stations, the 62-year-old former head of the domestic security service won 51.5 percent of the vote, according to data published on CENI's website.

Ghazouani had already declared himself the winner in the early hours of Sunday in the presence of current president Mohamed Ould Abdel Aziz, his supporters and journalists.

Out of the other five candidates, Biram Ould Dah Ould Abeid came second with 18.58 percent of the votes and Mohamed Ould Boubacar followed in third place with 17.82 percent, the CENI data showed.

Biram Ould Dah Ould Abeid, together with leading opposition candidates Sidi Mohamed Ould Boubacar, had complained of balloting irregularities and the expulsion of representatives from some polling stations, while CENI said no major problems had been reported. 

Ghazouani - who campaigned on the themes of continuity, solidarity and security for the nation - served as Abdel Aziz's chief of staff from 2008 to last year.

Preliminary results had originally been expected on Monday.