UNITED NATIONS — Secretary-General Ban is rejecting an assertion by Al Qaeda’s second in command that the United Nations is an enemy of Islam.

Ayman al-Zawahri’s justification of a terrorist attack against the U.N. headquarters in Algeria in December on the pretense that it was aimed at “Crusaders” is “totally false and unacceptable,” Mr. Ban said yesterday. But a former U.N. official, Lakhdar Brahimi, whom Mr. Ban appointed to investigate the Algiers bombing, recently indicated that he believes the world body is biased against Muslims, saying the United Nations needs to “work at restoring its credibility, independence, and impartiality,”

The U.N. General Assembly has been unable to agree on a definition of terrorism, with Arab member states demanding that all attacks aimed at “foreign occupation” — those against Israel, for example — be excluded from the designation. Still, the U.N, Security Council has listed Al Qaeda as a terrorist organization, along with the Taliban, since the attacks of September 11, 2001, on New York and Washington, D.C.

“The United Nations is an enemy of Islam and Muslims,” Mr. Zawahri said in a 103-minute audio message addressing a set of 100 questions posted on Al Qaeda-linked Web sites. The world body “is the one which codified and legitimized the setting up of the state of Israel and its taking over of the Muslims’ lands,” Mr. Zawahri said.

In between questions about killing people at markets and about Al Qaeda’s failure to hit targets in Israel, a man identifying himself as an Algerian student asked Mr. Zawahri about the legality of killing “innocents” in the December 11 bombing in Algiers. Forty-one people were killed in the attack, including 18 U.N. employees, all but four of them Algerian nationals.

They were not innocent, Mr. Zawahri said. “According to the communiqué from the brothers in Al Qaeda in the Islamic Maghreb, they are from the Crusader unbelievers and the government troops who defend them,” he said, Al-Jazeera’s English Web site reported. “If there was any innocent who was killed in the Mujahedeen’s operations, then it was either an unintentional error, or out of necessity.”

The United Nations has sanctioned the presence of “Crusaders” in Afghanistan and Iraq, and approved the separation of East Timor from Indonesia, Mr. Zawahri said. At the same time, he added, the world body “doesn’t recognize that [right] for Chechnya, nor for all the Muslim Caucasus, nor for Kashmir, nor for Ceuta and Melilla, nor for Bosnia.”

U.N. officials have said they are aware of their organization’s increasingly negative image among Muslims. Mr. Ban last week issued a strong rebuke of a short Dutch film, “Fitna,” calling it offensive and anti-Islamic.

“There is no justification for hate speech or incitement to violence,” Mr. Ban said in a statement. “The right of free expression is not at stake here.”

A U.N. spokeswoman, Marie Okabe, said Mr. Ban, who yesterday attended the NATO summit in Romania, watched “Fitna” before issuing his statement.