Members of al-Qaeda's North Africa wing say they carried out two suicide attacks that have killed at least 50 people in Algeria in the past two days.
Hospital officials in Dellys warned the number of the dead could rise
The group, which calls itself al-Qaeda in the Islamic Maghreb, made the claim in an internet statement.
In the latest attack, at least 30 people died on Saturday when a truck packed with explosives drove into a naval barracks in the port of Dellys.
Authorities in Algeria have called for rallies against violence on Sunday.
The UN and EU condemned the bombings. The chairman of the UN Security Council, Jean-Maurice Ripert, called Saturday's bombing a heinous terrorist attack.
Terrorism 'in retreat'
Hospital officials have warned the number of the dead could rise in the latest bombing in Dellys, 100km (60 miles) east of Algiers.
It comes just two days after more than 20 people died in Batna when a man blew himself up among a crowd that was expecting the arrival of President Abdelaziz Bouteflika.
More than 30 people were killed in similar bombings in Algiers in April.
The BBC's North Africa correspondent Richard Hamilton says the admission does not really come as a surprise because analysts say the attacks bore the hallmark of al-Qaeda, which has imported the tactic of suicide bombing into the region.
The militant group was previously known as the Salafist Group for Preaching and Combat (GSPC) but changed its name when it joined forces with al-Qaeda last year.
After the latest attack, Mr Bouteflika insisted terrorism was in retreat "despite the distressing and hurtful consequences of these operations that have targeted the Algerian people".
Speaking on Algerian television, he said that by targeting innocent people the attackers had betrayed "their people, their country, their religion".
The vast majority of Algerians distance themselves from the extremists and after decades of war say they are tired of bloodshed, our correspondent says.