Rescuers scoured masonry and debris on Wednesday for survivors from a twin bombing in the Algerian capital that killed dozens and showed al Qaeda retains the ability to strike despite recent reversals.

The group said its attack on U.N. offices in Algiers' affluent Hydra district and the Constitutional Court in nearby Ben Aknoun area had struck the slaves of America and France.

My brother is still trapped. He is a driver, said a man who gave his name as Djamel.Who'll care for his four children?

I could not sleep last night -- my sister is under the wreckage. I hope she will be pulled out alive, said another onlooker, Farid.

I'm here to ask for good news about my cousin. He is under the debris. I don't understand why I'm not allowed access to the wreckage. I'm ready to help, said Manel Djidi.

Seven people were pulled alive from the wreckage overnight.

Foreign Minister Mourad Medelci told Europe 1 television the official death toll was 30, while a Health Ministry source on Tuesday said 67 people were killed.

Algerian radio said the dead included three Asian nationals, a Dane and a Senegalese. Ten of the dead were U.N. staff.

The second al Qaeda attack on the Mediterranean capital in eight months plunged many residents into nervous gloom, an all too familiar mood in a city of 3 million buffeted by political bloodshed during an undeclared civil war in the 1990s.

The narrow streets of the hillside city, habitually clogged with traffic, were quieter than usual as many stayed at home.

I'm afraid it's going to be like before, said a pedestrian on Algiers' main Didouche Mourad street, referring to the 1990s.

A man reading a newspaper at a sidewalk cafe nearby said: You can be sitting at a table like this drinking your coffee and a bomb can explode right in front of you.

The problem is, this keeps on happening, said another man, referring to an April 11 bombing in Algiers that killed 33.

EXTREME CAUTION

Over the summer security forces killed or captured the guerrillas who orchestrated the April blasts, but al Qaeda's bombing on Tuesday showed it retains its menace.

Many of the few thousand expatriates in Algiers kept a low profile. The U.S. embassy said it was open for business as usual but was implementing more robust security procedures while we assess the current security situation.

The travel advice section on the British embassy Web site mentioned Tuesday's bombings and commented that you should exercise extreme caution at all times.

Al Qaeda's North African wing said on an Internet site that two of its suicide bombers carried out the attacks and that the United Nations and Algerian government were the targets. No independent verification of the statement was available.

We bring good tidings to the nation of Islam that a group of its children carried out two martyrdom operations ... to inflict harm on the crusaders and their agent, the slaves of America and France, its statement said.

Al Qaeda's North African wing, which wants all foreigners to leave Algeria, claimed responsibility for the April blast and other blasts east of the capital this year that have worried foreign investors.

Many Algerians are still traumatized by violence that began in 1992 when the then army-backed government scrapped an election that a radical Islamic party was set to win.

Up to 200,000 people were killed, but the violence subsided for several years before spiking up again in late 2006.

(Writing by William Maclean, Editing by Elizabeth Piper)