Mauritanians are voting for the first time since the country gained independence from France in 1960.
The 62-year-old is standing down after serving the maximum two five-year elected terms.
However the status quo is likely to prevail when a new leader is elected.
Abdel Aziz has expressed his support for Mohamed Ould Ghazouani, who is a former general and defense minister.
Pakistan steps up diplomatic bid to get US-Iran peace talks on track
Pakistan stepped up diplomatic efforts on Thursday to hasten US and Iran peace talks, as Tehran said it was reviewing Washington's latest responses and President Donald Trump suggested he could wait a few days for "the right answers".
Philippines vows to arrest fugitive senator wanted by ICC
The Philippine justice minister on Thursday ordered law enforcement to apprehend a senator wanted by the International Criminal Court and said authorities had leads on his whereabouts, a day after a court denied his bid to prevent his arrest.
UN condemns Israeli decision to establish military facilities in East Jerusalem
United Nations Secretary-General António Guterres has strongly condemned Israel's decision to establish military facilities in one of the UN's compounds in the Sheikh Jarrah neighbourhood of East Jerusalem.
Canada PM Carney says Israel's treatment of Gaza flotilla members is 'abominable'
Israel's treatment of detained Gaza flotilla activists is "abominable", Canadian Prime Minister Mark Carney said Wednesday, following the release of a video showing Israeli police forcing activists to kneel on the ground in rows with their hands tied behind their backs.
Tankers exit Hormuz as Trump, Vance talk up Iran deal prospects
Two Chinese tankers laden with oil exited the Strait of Hormuz on Wednesday, shipping data showed, brightening hopes that the US-Israeli conflict with Iran may soon be resolved after positive comments from president Donald Trump and his deputy.
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