ALGIERS - "It's cowardice," U.N. development worker Naima Silarbi said of those behind the bombing which destroyed the world body's Algeria office.

"If you love your country you build it, you don't destroy it," the 34-year-old woman, her face criss-crossed with scars caused by Tuesday's blasts, told visiting U.N. Development Program Administrator Kemal Dervis.

Dervis, who flew in to inspect the attack site and discuss security with the government, visited those who were wounded in Algiers after car bombs claimed by al Qaeda killed at least 11 U.N. employees and more than 20 other people in the capital.

"I'm here to offer my support to the families of those killed in the attacks and send to the Algerian people the strong message of solidarity from the U.N.," Dervis told a news conference on Thursday.

Al Qaeda's North African wing claimed responsibility for the bombs, saying it had targeted what it called "the slaves of America and France".

The bomber of the U.N. offices was identified by security sources as veteran Algerian Islamist fighter Bechla Rabeh, who was in his 60s.

Experts say he was selected to combat signs of unease within the armed group over its habitual use of youths -- many of them suspected of being brainwashed or drugged -- as suicide bombers.

"They think they are heroes because they have the courage to ram a car against a wall, but it's an act of cowardice, nothing more," Silarbi said.

"We work to reduce poverty, fight disease and help local populations. We work for the good of this country."

SEARCH FOR SURVIVORS

Sobbing relatives of some of the dead met Dervis on Wednesday evening at the site of the blast in the city's Hydra area, as emergency services dug through debris for possible survivors.

During his visit one body was pulled out. Seven people have been pulled alive from the mass of crumpled masonry.

Dervis said the United Nations was boosting security at its offices around the world after the attacks, but he said this would need more funding.

"We do have some resource problems. It (security) is not a free good," he said. "We have to mobilise the resources to do better."

He said the U.N. was talking to the government about a move out of Hydra as part of efforts to improve security.

"U.N. will resume activity in Algeria after a short time without reducing staff but we will take tough security measures," Dervis added.

He said he had been moved by his visit to the wounded.

"These are not soldiers. They are development workers. They didn't sign up for battle. They signed up for development work so it is our duty as the international community to help them".

Another U.N. worker, Leila Souilamas, told Dervis she felt lucky to be alive.

"Two floors of the building fell on me. It is a miracle I'm alive," she said.

U.N. Secretary General Ban Ki-moon said the bombs were "a despicable strike against individuals serving humanity's highest ideals under the U.N. banner" and "an attack on all of us".