Algeria journalist jailed in pre-trial detention
"Our correspondent in Algeria, Khaled Drareni, has been incarcerated," RSF secretary-general Christophe Deloire wrote on Twitter.
"We will fight against this unfair and arbitrary decision," he added.
Drareni was arrested on March 7 while covering an anti-government protest, accused of "inciting an unarmed gathering and damaging national integrity".
He was released three days later but re-arrested on Friday evening.
Read more: Quarantined for now, Algeria's protesters vow to return
RSF has condemned what it called the "shameless use" of the coronavirus epidemic "by the Algerian regime to settle scores with free and independent journalism".
Prisoners' rights group CNLD said on Facebook that Drareni appeared Sunday before a prosecutor in an Algiers court in the presence of defence lawyers, adding that he was in good health.
Souhaieb Khayati, RSF's North Africa chief, told AFP that Drareni was being held in the capital's El Harrach prison under "preventive detention until a trial date has been set".
Drareni is also the founder of the Casbah Tribune website and Algeria correspondent for international French-language channel TV5 Monde.
He has been arrested several times for covering "Hirak" anti-government protests that had been held in the capital Algiers every Friday since February 2019.
The demonstrations were suspended this month over the coronavirus, which has killed 29 people and infected 454 in Algeria, according to official figures.
Despite the pandemic, Algeria's courts have carried on work, with Karim Tabbou - a key figure in the anti-government protests - sentenced to a year in prison last Tuesday.
Two other journalists, Sofiane Merakchi and Belkacem Djir, are currently in jail in Algeria.