An Algerian military judge on Sunday placed in custody the youngest brother of former President Abdelaziz Bouteflika and two former intelligence chiefs, state TV reported.
Said Bouteflika and the two generals, Athmane Tartag and Mohamed Mediene, were arrested on Saturday, it said.
The three are under investigation over "harming the army's authority and plotting against state authority," it said, quoting a statement from the prosecutor at the military court of Blida, south of Algiers.
It did not elaborate on the allegations but the news that the three have been detained may go some way to satisfying protesters in Algeria who have demanded an broad overhaul of the political system since President Bouteflika stepped down last month.
Said Bouteflika, who served as a top advisor to the presidency, acted as Algeria's de facto ruler after his brother suffered a stroke in 2013 that left him in a wheelchair.
Mediene had been intelligence chief for 25 years until his dismissal by Bouteflika in 2015.
Massive protests calling for a radical change to Bouteflika's government pushed the ailing president to resign on April 2. Demonstrators continue to demand the removal of all those linked the former administration.
Army chief of staff Ahmed Gaed Salah has promised to rid the country of corrupt politicians, oligarchs and military officials in order to restore confidence among the people.