Meanwhile, Western countries have reduced embassy services in Algeria and urged their citizens to avoid travelling on predictable routes after Wednesday's attacks.
Responsibility for the bombings, which followed closely multiple suicide blasts in neighbouring Morocco, were claimed by al-Qaeda organisation in the Islamic Maghreb in a phone call on Wednesday to Al Jazeera's bureau in Rabat, the capital of Morocco.
A man identifying himself as Abu Mohammed Salah said that three al-Qaeda members had carried out suicide truck bombings. The targets were the Algerian government building in the capital, the headquarters of Interpol and the judicial police headquarters in Bab Ezzouar, a suburb of Algiers.
In Washington, both the White House and the US state department have condemned the attacks.
Sean McCormack, the state department spokesman, said: "These horrific acts indiscriminately killed members of the security services and civilians alike.
|"These were odious and cowardly acts"|
Javier Solana, European Union foreign policy chief
"The United States condemns the terrorist attacks."
Dana Perino, White House spokeswoman, said US authorities were already working with their Moroccan and Algerian counterparts.
She said: "We stand with them as they try to find out the cause or the impetus for the attacks."
In the phone call to Al Jazeera, Salah said the Algiers attacks were "targeting the alliance of Crusaders and their governments, tracing them wherever they are, defending our brothers the oppressed all over the world, and defending our brothers the detainees, prisoners and oppressed ones in Morocco, Algeria, Mauritania or others".
The al-Qaeda affiliate published photographs of what it said were the three Algiers suicide bombers in an internet statement and said the bombings killed at least 53 people.
Central Algiers blast
The first of Wednesday's attacks was carried out by a bomber who drove an explosives-laden truck into a guard post outside the government headquarters in central Algiers, police said.
At least 12 people were killed and 135 injured, according to the civil defence department.
Minutes later, bombers driving two trucks triggered explosions in the eastern suburb of Bab Ezzouar, on the road to the international airport and not far from one of Algeria's largest universities.
Another 12 people were killed and 87 wounded in the blasts that demolished an electricity sub-station and badly damaged a police station, the civil defence department said.
Jacques Chirac, the French president, condemned what he called the "terrible attacks" in a message of solidarity to the president of Algeria, which was a French colony until 1962.
The Arab League condemned "these terrorist acts and what they represent and aim to achieve."
|Algeria has seen an upswing in violence recently [Reuters]|
Russian President Vladimir Putin expressed "sorrow and indignation".
The Iranian government called the attacks "inhuman and hideous".
The blasts come as the Algerian authorities are struggling to curb an upswing in violence.
At least 33 people, including about 15 security officers, have been killed in clashes with armed groups since the beginning of April, according to official figures and media reports.
In February 2006, the government offered an amnesty to any fighters who surrendered.
The Algerian army has been involved in a 20-day offensive in the eastern region of Kabylie against al-Qaeda's unit that claimed Wednesday's attack.
Previously known as the Salafist Group for Preaching and Combat, it recently changed its name to reflect a direct affiliation with Osama bin Laden's network.