Muslims in Afghanistan gave Washington three days to offer a response to a Newsweek story that claimed the Islamic holy book was desecrated at the American prison in Guantanamo Bay, but the magazine apologized yesterday for its report that prompted deadly riots across Afghanistan last week.

Reaction across the Islamic world has been strong, with daily demonstrations since the May 9 story came out. At least 15 people died in Afghanistan after protests broke out Tuesday following the report that interrogators at Guantanamo Bay, Cuba, placed Korans in washrooms to unsettle suspects, and in one case, “flushed a holy book down the toilet.”

Many of the 520 inmates at Guantanamo are Muslims arrested during the American-led war in Afghanistan. In both Afghanistan and Pakistan, insults to the Koran and Islam’s prophet, Muhammad, are regarded as blasphemy and punishable by death.

“The American soldiers are known for disrespect to other religions. They do not take care of the sanctity of other religions,” the Pakistani chief of a coalition of radical Islamic groups, Qazi Hussain Ahmed, said yesterday.

Mr. Ahmed’s comments came a day after Pakistan’s president, General Pervez Musharraf, and Prime Minister Aziz, both allies of Washington, demanded an investigation and punishment for those behind the reported desecration of the Koran.

In Afghanistan, Islamic scholars and tribal elders called for the punishment of anyone found to have abused the Koran, said the head of the religious affairs department in Badakhshan province, Maulawi Abdul Wali Arshad.

Mr. Arshad and the provincial police chief said the scholars met in Faizabad, 310 miles northeast of the capital, Kabul, and demanded a “reaction” from American authorities within three days.

But Newsweek apologized in an editor’s note for today’s edition and said they were re-examining the allegations.

“We regret that we got any part of our story wrong, and extend our sympathies to victims of the violence and to the U.S. soldiers caught in its midst,” Newsweek’s editor, Mark Whitaker, wrote.

Mr. Whitaker wrote that the magazine’s information came from “a knowledgeable U.S. government source,” and before publishing the item, writers Michael Isikoff and John Barry sought comment from two defense department officials. One declined to respond, and the other challenged another part of the story but did not dispute the Koran charge, Mr. Whitaker said.

But on Friday, a top Pentagon spokesman told the magazine that a review of the military’s investigation concluded “it was never meant to look into charges of Koran desecration. The spokesman also said the Pentagon had investigated other desecration charges by detainees and found them ‘not credible.'”

Also, Mr. Whitaker wrote, the magazine’s original source later said he could not be sure he read about the alleged Koran incident in the report they cited and it might have been in another document.

“Top administration officials have promised to continue looking into the charges, and so will we,” Mr. Whitaker wrote.

President Bush’s national security adviser said yesterday the allegation was being investigated “vigorously.”

“If it turns out to be true, obviously we will take action against those responsible,” Stephen Hadley said in an interview for CNN’s “Late Edition.”

Mr. Ahmed, the religious leader in Pakistan, said Islamic groups in Pakistan, Egypt, Malaysia, Britain, and Turkey would hold protests on May 27 against the alleged desecration.

Lebanon’s most senior Shiite Muslim cleric yesterday said the reported desecration of the Koran is part of an American campaign aimed at disrespecting and smearing Islam.

Grand Ayatollah Mohammed Hussein Fadlallah urged Muslims and international human rights organizations “to raise their voices loudly against the American behavior, which is hostile to Islam and Muslims.”

In a statement faxed to the Associated Press, Ayatollah Fadlallah called the alleged desecration a “brutal” form of torture. “This act is not an individual act carried out by an American soldier, but rather it is part of the American behavior of intellectual and psychological education in disrespecting Islam and smearing its image in the souls of Americans,” Ayatollah Fadlallah said.