Onetime Al Qaeda loyalists now fault it

"Were we insane killers of innocents as the questioner claims, it would be possible for us to kill thousands of them in the crowded markets," Zawahiri responded. The deaths of any innocents were the result of "unintentional error or out of necessity. . . . The enemy intentionally takes up positions in the midst of the Muslims for them to be human shields for him."

Others asked about Al Qaeda's legal authority, and questioned why Zawahiri criticizes the militant groups Hamas and Hezbollah, which are fighting Israel, for their participation in politics.

Zawahiri's often-rambling explanations referred listeners to his recently released book, "The Exoneration," which primarily rebuts statements by Sharif, whom Zawahiri suggests was coerced into criticizing Al Qaeda. Sharif denies that.

Such criticism ultimately could undermine Al Qaeda, said Frank Cilluffo, a former White House counter-terrorism official who is director of the Homeland Security Policy Institute at George Washington University.

"It has raised the bar in using violence to achieve its objectives, and people are starting to ask a lot of hard questions. It is losing popular support," he said. "It is occurring within the strategic thinkers, but also among the rank and file."

Some of the earliest manifestations of the dissent were in Iraq. The first leader of Al Qaeda in Iraq, Abu Musab Zarqawi, killed so many Shiite and Sunni Muslims that a 2005 letter allegedly from Zawahiri told him to stop.

The violence continued after Zarqawi was killed by U.S. forces in 2006, and angry Sunnis were driven to form councils of neighborhood volunteers with U.S. support to counter the foreign fighters that helped make up Al Qaeda in Iraq.

In North Africa, some radicals have rebelled against a merger with Bin Laden's network, objecting to the wave of suicide bombings that have killed women and children since last April, as well as to efforts to send the group's young men to Iraq.

Several prominent members of the Al Qaeda affiliate, including regional commander Benmessaoud Abdelkader, have charged that suicide bombings serve Al Qaeda's global ambitions at the expense of their efforts to fight what they view as corrupt and anti-Islamist governments in Algeria, Morocco and elsewhere in North Africa.