Mobile internet has been cut since Monday night in Mauritania's capital, AFP journalists saw, after scuffles broke out following the announcement that incumbent Mohamed Ould Cheikh El Ghazouani had won the presidential election.
Witnesses reported disturbances in working-class districts of Nouakchott on Monday evening, hours after final provisional results showed that Ghazouani had comfortably won re-election in Saturday's presidential poll.
The witnesses did not specify the extent of the disorder to AFP.
Nouakchott appeared calm on Tuesday, with businesses open as usual.
The authorities have not commented on the mobile internet cuts.
Internet restrictions have become a common tactic by governments around the world in the face of protests.
Second-place candidate, anti-slavery activist Biram Dah Abeid, on Monday denounced "massive fraud" and threatened peaceful street demonstrations.
Abeid said he was waiting for his own teams to provide election results before taking a "final decision".
The aftermath of the 2019 election, which brought Ghazouani to power, was marked by clashes and the arrest of opponents as well as nationals of neighbouring countries accused of taking part in demonstrations.
It was also accompanied by a 10-day internet blackout.