ALGIERS, Algeria - Al Qaeda's North African affiliate claimed responsibility Sunday for a car bombing that killed 30 Algerian coast guard officers and another recent blast that ripped through a crowd waiting for the country's president.

The group has carried out a spate of recent bombings that have shattered the Algerian government's efforts -- successful until recently -- to restore calm after a 15-year Islamist insurgency.

"We swear to God to continue (to) sacrifice our lives until you stop supporting the crusaders in their war, apply the Islamic tenet and stop your war against God's religion,'' the group said in a statement posted on an Islamic website.

Both bombings targeted symbols of the Algerian state at a time when the government has toughened its tone and intensified military crackdowns on Islamic militants hiding out in remote scrubland. Interior Minister Noureddine Yazid Zerhouni warned terrorists Friday that they have "one choice: turn themselves in or die.''

In the most recent blast, on Saturday, explosives planted in a van ripped through barracks in the northern coastal town of Dellys, about 50 kilometres from Algiers. The bombing appeared timed to kill as many officers as possible, when they were grouped together to raise the flag.

It was not clear whether the bomber was killed in the blast or escaped.

The 30 victims were all coast guard officials, who are part of Algeria's armed forces, hospital authorities said, speaking on condition of anonymity because they were not authorized to speak to media. Some 20 others were injured.

The bombing was Algeria's deadliest since April, when triple suicide bombings against the prime minister's office and a police station killed 32.

Another attack this week killed at least 22 in a crowd of people in eastern Algeria who were waiting to see visiting President Abdelaziz Bouteflika, who has devoted his eight years in office to ending violence by insurgents, and whose government is a U.S. ally in the war against terror.

There was speculation that Bouteflika was the intended target in the Thursday attack, though officials kept silent on the question.

Algeria's insurgency broke out in 1992, after the army cancelled legislative elections that a now-banned Islamic fundamentalist party appeared poised to win. Up to 200,000 people were killed in the ensuing violence.

Widespread killing was on the wane until recently, but violence surged this year after Algeria's Salafist Group for Call and Combat, or GSPC, officially linked up with al-Qaida, taking the name Al Qaeda in Islamic North Africa.

The group has claimed responsibility for other attacks this year, including the triple suicide attacks in April and another blast in July, when a suicide bomber blew up a refrigerated truck inside a military encampment, killing 10 soldiers. Besides targeting the military and symbols of the state, militants have also killed foreigners in smaller-scale attacks.

Over the years, Bouteflika's government has offered amnesty for reformed militants while waging tough military crackdowns on those who refused the offers -- a strategy that Bouteflika promises will reconcile the nation.

Those tactics have dramatically reduced the number of fighters, and the GSPC may have joined up with al Qaeda partly as a way to survive and attract a new generation of fighters.

"To recruit, they can say, we are in international jihad, we need to help our brothers in Iraq, and Afghanistan, not just fight in Algeria,'' said Louis Caprioli, the former assistant director of France's DST counterintelligence agency, who now works for risk-management company Geos.

Despite the spate of attacks, Algerian officials have repeatedly insisted that Al Qaeda in Islamic North Africa is weak from internal disputes and ready to implode. Prime Minister Abdelaziz Belkhadem said Saturday that terrorism was in "decline'' in Algeria, and that militants "have never succeeded, in 17 years, in their desperate need to strike at the country's stability.''

The new bombings were militants' "response to leaders, to show them, 'you are wrong, look at our operational abilities,''' Caprioli said.