Ten people were jailed after taking part in violent protests in the Niger capital Niamey against measures aimed at containing the coronavirus pandemic, police said on Tuesday.
The measures include a nighttime curfew and a ban on collective prayers, with the holy Muslim month of Ramadan approaching at the weekend.
Those jailed were among 108 protesters who were arrested between Friday and Sunday, a police statement said.
They are being held in the high-security Koutoukale prison some 60km outside Niamey, the statement said.
Residents of several districts of the capital clashed on Sunday with security forces against the confinement measures.
"Organised individuals set about burning tyres and attacking private property," the Niamey regional governor, Issaka Assane Karanta, said on state television Tuesday. "Many neighbourhoods were torched."
He said assailants on motorcycles were seen placing tyres and petrol-filled jerrycans around the city, adding: "Everything was well planned, well organised."
Residents in the working-class district of Lazaret said security forces fired tear gas to disperse worshippers who were gathering to pray at a mosque.
A riot quickly ensued, with mainly youthful protesters burning tyres and setting roadblocks, the residents said, quoting them as shouting slogans such as "the struggle continues" and "don't back down".
A security source told AFP that similar protests had taken place earlier on the outskirts of Niamey.
Niger, one of the world's poorest countries, has officially recorded 20 deaths from among 655 cases of Covid-19 since March 19.
On April 12 the government extended Niamey's isolation from the rest of the semi-desert country as well as a state of emergency and the curfew. Places of worship and schools are shut.
The former French colony is also battling frequent attacks by jihadist groups in the west along its borders with Mali and Burkina Faso, and in the southeast on its border with Nigeria.