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.
Sources say Azerbaijan Airlines flight was downed by Russian air defence system
An Azerbaijan Airlines flight that crashed in Kazakhstan on Wednesday was downed by a Russian air defence system, four sources in Azerbaijan with knowledge of the investigation told Reuters.
Thousands mark 20 years after deadly Indian Ocean tsunami
Survivors and families of victims of the Indian Ocean tsunami 20 years ago visited mass graves, lit candles and comforted one another across Southeast and South Asia in ceremonies on Thursday to mark the disaster that killed some 230,000 people.
Russia says it prevented Ukrainian plots to kill high-ranking officers
Russia's Federal Security Service (FSB) said on Thursday that it had foiled several plots by Ukrainian intelligence services to kill high-ranking Russian officers and their families in Moscow using bombs disguised as power banks or document folders.
Israeli airstrike kills five journalists in central Gaza
Five Palestinian journalists were killed when their marked media van was struck by an Israeli airstrike in central Gaza's Nuseirat on early Thursday, the enclave's health authorities said.
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