(CNN) -- The second-in-command of al Qaeda has said the terrorist group does not kill innocents and that its leader Osama bin Laden is healthy, according to a transcript of an audio tape released by radical Islamist Web sites.

An image of Ayman al-Zawahiri taken from an earlier videotape.

Ayman al-Zawahiri made his remarks in response to questions solicited on a Web site close to al Qaeda.

The questions asked his views about Egypt and Iraq as well as Hamas, the militant Islamic group that seized control of Gaza last year.

They also referred to attacks by al Qaeda and affiliated groups that have killed scores of civilians in Muslim nations, such as Algeria, Iraq and Morocco.

Al-Zawahiri, who led an Egyptian Islamic militant group that joined forces with bin Laden in the 1990s, said innocents who have been killed in attacks by al Qaeda or affiliated groups died as a result of "unintentional error" or because they were used as "human shields" by "the enemy."

Governments worldwide have blamed al Qaeda for attacks that have killed several thousand people, including about 3,000 who died in the attacks on Washington and New York on September 11, 2001.

Al-Zawahiri defended a December attack in Algeria -- hospital sources said it killed 60 people -- because one of its targets was a United Nations building and the "United Nations is an enemy of Islam and Muslims," according to the transcript.

He said "bin Laden is healthy and well," the transcript said, but that even if he "doesn't become ill, he must die one day."

Al-Jazeera broadcast an audiotape last month on which a voice identified as bin Laden's declared "Iraq is the perfect base to set up the jihad to liberate Palestine."

Bin Laden, who was behind the terrorist network's September 11 attacks, has been in hiding since the U.S. assault on Afghanistan that followed those strikes.

He is rumored to have faced health troubles or to have been wounded in an attack, although nothing conclusive has been found.

He is believed to be hiding somewhere in the mountainous region of the Pakistani-Afghan border. The United States has posted a $25 million reward for his capture. E-mail to a friend

All About Israel • Ayman al-Zawahiri • Al Qaeda