Algerian President Abdelaziz Bouteflika dismissed national police chief Mustapha Lahbiri earlier this week, the interior ministry said in a statement that gave no reason for the move.
Mr Bouteflika had named Mr Lahbiri to the post in June 2018, replacing Abdelghani Hamel who had been in the post for eight years and was also fired without reasons provided.
Analysts and local media linked Mr Hamel's removal to the seizure of 701 kilograms of cocaine at the western port of Oran at the end of May, and the handling of the subsequent investigation.
The statement said Abdelkader Kara Bouhadja, hitherto director of the judicial police, would take over from Mr Lahbiri.
Mr Bouteflika said last Sunday he would seek a fifth term in a presidential election set for April 18, according to the state news agency APS, ending months of uncertainty caused by his poor health.
The 81-year old leader has been in office since 1999 but hasn't been seen in public often since suffering a stroke in 2013 that confined him to a wheelchair, is likely to be re-elected as Algeria's opposition remains weak and fragmented.
His decision stirred mixed reactions on Monday in the Algerian press, with one newspaper describing it as risky as "Russian roulette" and another welcoming his pledge of reforms.