According to a ministry statement released by the state-run news agency, APS, the migrants were detained on several boats between Thursday and Saturday.
The number of illegal migrants detained in the North African nation has increased quarter by quarter, with 592 for the first quarter and 795 for the second and 1,243 for the third, according to the Defense Ministry.
Algeria has signed cooperation agreements with some European states to reduce illegal immigration.
Algerian authorities have launched a massive crackdown on migrants in recent months, rounding up hundreds and deporting them to their native countries. The dire deportation conditions were denounced by human rights watchdogs.
Human Rights Watch said more than 3,000 had been expelled in the past two months, including pregnant women, new-born babies and unaccompanied children.
There are around 100,000 African migrants in Algeria, most from Mali, Niger and Burkina Faso. Human Rights Watch documented a previous roundup of more than 1,400 sub-Saharan migrants in December 2016.