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.
Hong Kong court finds tycoon Jimmy Lai guilty in landmark security trial
Hong Kong's High Court on Monday found pro-democracy campaigner Jimmy Lai guilty of conspiracy to collude with foreign forces and to publish seditious material under a China-imposed national security law that could see him jailed for life.
Ukraine peace talks stretch into second day at start of pivotal week for Europe
Ukrainian President Volodymyr Zelenskyy will resume talks with US President Donald Trump's envoys in Berlin on Monday, after the US side said a "lot of progress" had been made on ending Europe's deadliest conflict since World War II.
Flash floods kill at least 37 people in Morocco's Safi province
At least 37 people have been killed in flash floods triggered by torrential rains in Morocco's Atlantic coastal province of Safi, Moroccan authorities said on Monday.
'Hero' who disarmed Bondi gunman recovering after surgery, family says
A Sydney resident who wrestled a gun from one of the alleged attackers during the mass shooting at Bondi Beach is recovering in hospital after undergoing surgery for bullet wounds to his arm and hand, his family said.
School bus accident in Colombia kills 17, injures 20
Seventeen people were killed and 20 injured after a bus carrying school children fell off a cliff in a rural area in northern Colombia, the local governor said on Sunday night.
