A suicide car bombing at a police academy in the Les Issers district of Boumerdes, some 55 km east of the capital, Algiers, killed 43 and wounded 45 people. Earlier in the day 11 servicemen and a civilian were killed in an ambush by armed militants 350 km east of the capital.
"We express our sincere condolences to the relatives and friends of those killed and wounded and resolutely condemn the latest bloody terrorist atrocities," Andrei Nesterenko, a spokesman for the Russian Foreign Ministry, said in a statement. "We confirm our solidarity with friendly Algeria and our support for the actions of the authorities in the eradication of terrorism."
No one has so far claimed responsibility for the attacks.
Last December the North African arm of terrorist group al Qaeda claimed responsibility for two truck bombings outside a United Nations building in Algiers, which killed about 30 people, including UN staff.
Algeria was engulfed in violence after the military scrapped 1992 elections that the Islamic Salvation Front had been expected to win. More than 100,000 people died during the subsequent insurgency.
In 2005, tensions eased after the government issued the Peace and National Reconciliation Charter, releasing more than 2,000 former Islamist guerrillas under an amnesty designed to put an end to the conflict.