The Algerian interior ministry says six men suspected of carrying out bomb attacks in Algiers in December have been arrested.
A large part of the UN building was destroyed in the blast
"With these arrests, all the attacks committed recently in the Algiers region have been cleared up," the ministry was quoted as saying.
The two suicide blasts on 11 December killed at least 41 people, including 17 United Nations staff.
The North African branch of al-Qaeda said it carried out the two attacks.
The ministry said the suspects included a computer expert, three businessmen and a delivery driver, adding that their leader, Abderrahmane Bouzegza, was killed by the army on 28 January at Boumerdes, east of the capital.
The interior ministry said the blasts were the work of the El Farouk Brigade, which was responsible for a number of other attacks in the last two years. El Farouk Brigade is part of al-Qaeda in the Islamic Maghreb.
The double car bombing in the Algerian capital targeted the UN refugee agency and a government building.
The attack prompted the UN to appoint a panel to investigate the security conditions at its offices across the globe. UN Secretary General Ban Ki-Moon has appointed the veteran Algerian diplomat Lakhdar Brahimi to lead the panel.
Algeria made it clear that it did not welcome the new investigation because it had not been consulted by the UN.
Earlier UN staff said the Algerian authorities had ignored requests before the bombings to tighten security around its buildings.