Thousands of people in Mauritania have attended demonstrations in the capital calling for President Mohamed Ould Abdelaziz to resign.
The opposition groups held peaceful "decentralised" rallies in the nine districts of Nouakchott.
Organisers said they opposed "anti-democratic" policies of the government.
Mr Abdelaziz took power in the North African country in a coup in August 2008, after forcing out a democratically elected government.
An umbrella group representing nine different protest groups issued a joint call for the president to resign.
"We demand that he leaves Mauritanians free to choose their own leaders at this difficult moment and reject all other alternatives," they said, in a statement quoted by AFP news agency.
The statement also accused the president of rigging elections held in 2009 which confirmed him in power and refusing to hold a serious national dialogue with opposition groups.
AFP said the protesters had dispersed by nightfall.
There were occasional protests in Mauritania last year inspired by the Arab Spring uprisings across the region.
In April, demonstrators were tear-gassed by police during a "day of rage" against the government.