The audio message, which was accompanied by a 46-page English transcript, was the first installment of answers to the more than 900 questions submitted by supporters, critics and journalists in December.

"We haven't killed the innocents, not in Baghdad nor in Morocco, nor in Algeria, nor anywhere else," he said on Wednesday according to the English transcript which, like the audio message, appeared on Websites linked to the group.

The answer was in response to the question "excuse me, Mr Zawahri, but who is it who is killing with Your Excellency's blessing the innocents in Baghdad, Morocco and Algeria?"

Al-Qaeda has taken credit for the destruction of the World Trade Centre which killed nearly 3,000 people in New York City in 2001, while its affiliates in Iraq, Afghanistan and Algeria regularly set off explosives in crowded urban areas that have taken thousands of lives.

"If there is any innocent who was killed in the Mujahideen's operations, then it was either an unintentional error or out of necessity," Zawahri added.

He went on to say that it was their opponents who killed innocents and also noted that "the enemy intentionally takes up positions in the midst of the Muslims for them to be human shields for him."